Science topic

Magnetic Materials - Science topic

Explore the latest questions and answers in Magnetic Materials, and find Magnetic Materials experts.
Questions related to Magnetic Materials
  • asked a question related to Magnetic Materials
Question
7 answers
I have learnt that a simple ferro magnetic fluid can be made by mixing Black Iron Oxide (Fe3O4) and a viscous fluid like oil. I purchased black oxide from a hardware store. When I bring the powder near a magnet (loudspeaker magnet - the only magnet at my disposal) it is not at all responding, why is that?
I saw many videos on the internet making ferromagnetic fluids by mixing black oxide and some viscous media.
My question is if it is working for them why is it not working for me? What went wrong?
Relevant answer
  • asked a question related to Magnetic Materials
Question
2 answers
For a lateral spin valve, why different non-local voltages can be measured when the two ferromagnets are parallel or antiparallel (as shown in the electrochemical potential diagram versus position)?
Figure credit: A. Hirohata, K. Yamada, Y. Nakatani, I.-L. Prejbeanu, B. Dieny, P. Pirro, and B. Hillebrands, “Review on spintronics: Principles and device applications,” Journal of Magnetism and Magnetic Materials, vol. 509, p. 166711, 2020.
Note: I have edited the figure a little for my own use.
Relevant answer
Answer
The answer can be derived from electrochemical potential (ECP) calculations and continuity of ECP, charge currents, and spin currents at interfaces.
Reference: S. Takahashi and S. Maekawa, “Spin injection and detection in magnetic nanostructures,” Phys. Rev. B, vol. 67, p. 052409, Feb 2003.
  • asked a question related to Magnetic Materials
Question
1 answer
Are there any students or professors with students interested in helping with research of Bob Lazar's Sport Model? I don't have much money, just the thrill of a whole new field of study, specifically , a link between electromagnetism and gravity. For more information, please see the attached presentation. Skip over project 1 and see project 2 and 3 used together at the end of the file. This research is for people with experience with microwave RF and microwave magnetic materials.
Relevant answer
Answer
Did you complete or find someone to work on project 3?
  • asked a question related to Magnetic Materials
Question
1 answer
I am working with a magnetic material in FDTD Lumerical. To see magnetic effects of the magnetic material, its permittivity tensor needs to be used. I have tried to use the permittivity tensor following the way given at https://optics.ansys.com/hc/en-us/articles/360034915173-Matrix-Transformation-Simulation-object. The problem is that I cannot change the element values. How can I change the values???
  • asked a question related to Magnetic Materials
Question
6 answers
Dear All,
Please inform me with freely downloadable link of an OPENSOURCE software for magnetic simulations. The opensource should be such that I can work on magnetic materials theoretically and can use it for publications as well absolutely free of cost.
Thank You In Advance.
Relevant answer
Answer
Hi depending on the scale of simulation you may have several options, previous answers consider ab-initio tools for fundamental properties.
On a larger scale micro-magnetic simulations are carried out and regularly published with open source tools like OOMMF and MuMax. https://math.nist.gov/oommf/
On an intermediate scale a very interesting project following an atomistic approach (i.e. able to describe as well antiferromangets, disorder, interdiffusion...) is vampire https://vampire.york.ac.uk
  • asked a question related to Magnetic Materials
Question
1 answer
I am trying to observe TMOKE effect [T(+M) - T(-M)]/T(0) in COMSOL. Where T(+M) and T(-M) refer to Transmission of nanostructure in opposite magnetic field directions, and T(0) in absence of any magnetic field. For this I am using an Au nanostructure on a BIG(Bismuth-Iron-Garnet) magnetic material supported on SiO2 substrate. I have tried changing the magnetic field direction by changing the signs of off-diagonal elements in permittivity tensor for magnetic material but the results are unchanged. I have also rotated the structure so that magnetic field directions goes opposite but again the result is same. That is T(+M) and T(-M) are same leading to non existance of TMOKE. But the original paper I am following shows TMOKE. Can someone figure out the reason??? How to change magnetic field direction in this situation. For reference I have attached the research papaer.
Relevant answer
Answer
Dear Muhammad Ikram, I hope you are safe and well!
Did you consider the off-diagonal values as: i*g?
You can consider i*m*g, where m is used in parametric sweep as -1, 0, 1.
It makes the magnetization inversion in a quickly way.
Further, what polarization are you exciting the structure? TM? TE? For TMOKE measures, it is important use TM wave and align the magnetic field component with the external magnetization. In 2D model, I usually set TM wave with Hz direction.
I hope I may help you in your studies!
Best regards!
  • asked a question related to Magnetic Materials
Question
3 answers
I am simulating a gold nanostructure embedded in a magnetic material (CoAg) on SiO2 substrate to calculate transmission and absorption for some optical properties. At certain dimensions of the nanostructure absorption as well transmission exceed unity. For example when nanostructure height is decreased beyond 60nm, the problem of A and T exceeding unit occurs. The same also occurs when other dimensional parameters at 60nm height are changed. A and T go on increasing with reduction in nanostructure height, that is, if at 60nm height, max absorption is 0.9, at 50nm it would be 7.5, at 40nm would be 25.4, at 30nm would be 70.5 etc. I have proof checked multiple times the port, PML and wave equation settings. Everything is fine there. Can anyone figure out the point behind the problem I am facing???
Relevant answer
Answer
I have faced this problem during my Microring resonator modeling. It may occur for several reasons. My thoughts are:
1) The error caused in Boundary conditions, periodic conditions, and variable definitions that directly interact with the simulations. (These can be the main reason)
2) Incorrect mesh size ( Mesh size must be very much smaller than the operating wavelength)
3) The improper refractive index definition of the material (Materials acting as the gain medium, which is not intended for your simulation I guess)
4) Error in Perfectly Matched Layer (PML). Check the distance of port to the PML layers
Please provide us an update about the right reason for the problem in your simulation. Thank you.
  • asked a question related to Magnetic Materials
Question
7 answers
How can one identify or confirm the co-existence of multiple magnetic behaviours (such as ferromagnetism (FM), superparamagnetism (SPM), paramagnetism (PM) etc) in a single compound?
What are the general criteria for their co-existence and what kinds (groups) of magnetic materials such behaviours are usually observed?
What is the significance of separately studying the components (eg. extracting the SPM components from the FM)?
Kindly provide relevant books and articles.
Thank you
Relevant answer
Answer
Dear Elangbam Chitra Devi,
The formula you present is a real headache. Its second term is correct both for paramagnets and superparamagnets as well. The only difference between those two classes of magnetic materials is in the 'elementary' magnetic moment: ~1 Bohr's magneton for paramagnets and ~104--106 Bohr's magnetons for superparamagnets. The last, third term, is fine for those two classes too, but only for fields H close enough to zero. In fact, it simply duplicates the behavior of the second term. However, it never goes to saturation, what is clearly nonphysical and was never observed. The same problem exists with the first term of your equation. In summary: this equation tries to describe the hysteresis loop of magnetic sample but shamefully fails for ferromagnetic components. In fact, the first term presents two parallel straight lines, never saturating (trying to simulate the upper and lower branch of hysteresis loop). In addition, the value of HC looses its meaning (of coercive field) when any of the two other terms is present.
I'm afraid that no paper based on the presented equation will be ever accepted for publication.
  • asked a question related to Magnetic Materials
Question
3 answers
I have one query about the magnetic moment obtained in the LaH3 system obtained after doping on the carbon atom in place of the H atom. The original system is nonmagnetic, after doping one C atom I suppose to get the magnetic moment of around 2.0 ub, but I am getting only 0.997ub.
I am attaching my input file here. I did the changes in the magnon card also but still no effect. If anyone is familiar with this type of problem, please suggest me. I'll be very thankful for any kind of suggestion.
Relevant answer
Answer
Dear Payal Wadhwa and Muhammad Mushtaq,
Thank you so much for your response.
Here are my input files.
About references, I did not get anything but some similar things I read in some papers then I concluded that I am giving two extra electrons in the system, and in this way, I should get the magnetic moment of 2.0ub.
I am observing the magnetic moment in the OSZ* for the complete system.
  • asked a question related to Magnetic Materials
Question
2 answers
When ferromagnet (FM) and antiferromagnet (AFM) are coupled, exchange bias can be generated at the interface of FM and AFM which acts as a bias field in the hysteresis loop.
I am particularly interested in the case that FM has perpendicular magnetic anisotropy (PMA) and the localized magnetization in AFM lies in the plane. In this case, it is possible to generate an in-plane bias field to the FM layer.
In a system like PtMn + Co/Ni multilayer, where the Curie (Neel) temperature TC (TN) are both very high ( > 300 C), a typical way to induce this in-plane bias field is by applying a large in-plane field (~ 1T) and annealing the sample at ~300 C, which is below TC. I assume that the annealing is required because it is not a good idea to heat the sample above TC and therefore change the property of the material.
Now, my question is: If I have a similar system (FM with PMA, in-plane AFM), but with room temperature > TC >TN, can I induce an in-plane field by applying a large in-plane filed above TN and then cool the sample to a temperature below TN?
Relevant paper:
Annealing to get bias field:
Neel temperature of AFMs:
Relevant answer
Answer
the is often a confusion between ferrimagnetic effect and ferromagnetic ;when you use YIG like material In the microwave range) its ferrimagnetic !
  • asked a question related to Magnetic Materials
Question
3 answers
I want to develop any magnetic material core and silver nanoparticle deposited on it.Please suggest me which magnetic material best for that job.(Ag @ any magnetic component) .
  • asked a question related to Magnetic Materials
Question
7 answers
To differentiate between two magnetic materials
Relevant answer
Answer
Rachid Chikri , I agree with Khusboo Rana bringing up NMR as a local probe, which is often particularly useful if the sample tends to contain magnetic impurities which shadow the intrinsic magnetic behavior at low temperatures. The main requirement is to have a suitable nucleus with a spin and reasonable sensitivity in the crystal structure. Should that not be the case, as an alternative the muon spin resonance (muSR) available at a number of facilities, could be considered...
  • asked a question related to Magnetic Materials
Question
5 answers
I want to conduct band calculation including spin-orbital interaction in CdSe,non magnetic material by using Wien2k. However, in input file I need to set direction of magnetization h,k,l.
CdSe is non-magnetic material,so I initially set 0,0,0 but error happened and Wien2k didn't work.
I also tried default setting 0,0,1 but result was different from that of quantum espresso,another first principle calculation software. Size of spin splitting was smaller. All of other settings are default. What is collect setting for h,k,l and the others.
I apologize that my English is difficult to understand,because I'm not good at English.
Relevant answer
Answer
What you're referring to is the spin quantisation axis not the magnetisation axis. In any calculation including spin-orbit coupling, regardless of the magnetic state, a direction must be defined for spin quantization axis to let the electrons behave as spinors. I strongly recommend you to keep it unchanged along 001. If you're system is non-magnetic, it will not have any effect on the total magnetisation and you'll still get 000 as the net magnetizsation.
  • asked a question related to Magnetic Materials
Question
4 answers
I have characterised magnetic materials with VSM. and determined SQR & K values. Is it possible to determine those values when materials not attained saturation from the M-H loop.? In the below-attached graph, only blue line alone attained saturation from my view. Is that so?
Relevant answer
Answer
Mathu Sridharpanday - I agree with Eric Hermanny - in case of mixed systems (para+ferro, ferro+ dia etc) it helps to measure out to higher fields making sure that the loops close and the high field regions allow to subtract the non-hystoretic contribution... Hope that helps, good luck!
  • asked a question related to Magnetic Materials
Question
8 answers
I carried out the VSM analysis for synthesized nanoparticles. Could you please guide me how can I calculate the particles size with results of VSM analysis? And what is the level of accuracy of this method?
Relevant answer
Answer
Dear all, the question was already discussed within RG. Which nanoparticles you are dealing with ? Please check the following link and the references therein. My Regards
  • asked a question related to Magnetic Materials
Question
5 answers
Basically, the magnetization will be increased up to a certain temp i.e blocking temp(Tb) then magnetization will be decreased. why this type of behavior shown.
what is the exact reason?
Relevant answer
Answer
Dear Ramkrishna Das Adhikari,
The following article will help you .
Thanks
N Das
  • asked a question related to Magnetic Materials
Question
4 answers
I was wondering if its a good idea to employ machine learning to predict NMR parameters in nanomaterials. There are some papers in the literature, but I don't know if there are open source codes.
Thanks!
Relevant answer
Many thanks!!
  • asked a question related to Magnetic Materials
Question
3 answers
I want to calculate the spin orbit coupling of a magnetic material by DFT based calculations, but I have no idea about this calculation. So please provide a detail information about this.
Relevant answer
Answer
Dear Md. Atikur Rahman,
Spin orbit interaction and corresponding change in Energy Levels can be done by DFT softwares like Quantum Espresso , VASP etc .
In Quantum Espresso , you choose properly the spin option and then find the calculated magnetism, Energy, Fermi Energy, Total Energy and also can find the Total DOS and Partial DOS .
You can also , I think , go through some articles to see how the spin orbit interaction changes the Hamiltonian.
Please see one such article attached herewith.
Thanks
N Das
  • asked a question related to Magnetic Materials
Question
11 answers
The former has higher Mc and Mr values as well.
Relevant answer
Answer
Dear Sneha,
I suggest to measure minor M(H) loops for both samples at the maximum applied field you use for your heating experiment. Namely, if the values you mentioned (Ms (34 emu/g) material (a) and Ms (18 emu/g) one (b)) are obtained say by measuring up to 20 kOe, but the field you apply for the heating experiment is only 200 Oe, you will be in a minor loop which is likely to show very different Ms and Hc than what you expect.
  • asked a question related to Magnetic Materials
Question
3 answers
The upper and lower left images are the morphology of the sample, and the right two images are MFM images.
Through these images, I would like to explain the domain differences in detail for the top and bottom samples.
But I don't know how to explain...
Relevant answer
Answer
Dear Yungeun Ha ,
Magnetic Force Microscopy is not a self-sustained technique. In a good MFM image (i.e. without tip-induced effects) you obtain a map of the magnetic charges, and you need to combine such a map with other information:
-The composition of your sample, the hysteresis loops and what you deduce from them, for instance what is the magnetic anisotropy.
-How the sample was prepared before the MFM imaging: is it a demagnetized state? Is it a remanent state after applying a certain magnetic field?
So, it is impossible to answer your question without knowing all these facts.
Besides, you should improve the MFM experiment, the magnetic contrast in your images is very small, i.e. we can barely distinguish the magnetic charges. You should try with different tips (i.e. having different characteristics) to enhance the signal, but without introducing irreversible changes.
  • asked a question related to Magnetic Materials
Question
4 answers
What is the exact relation between spin polarization and magnetic moment in any magnetic materials?
Relevant answer
Answer
Magnetization and spin polarization are not the same. The latter is a collective response of all electrons in a system (including carriers and non-carriers) to the time-reversal breaking. In other words, magnetization is a macroscopic property of a system, exhibited collectively by all magnetic centers no matter where they are located energetically with respect to the Fermi level. Spin polarization, on the other hand, is a microscopic property associated with only those electrons which contribute to current. More specifically speaking, It is a measure of imbalance in the population of Fermi carriers with opposite spins. A 100% spin polarization, thus, means at the Fermi level all the electrons can have the same spin character. In a half-metallic fully compensated ferrimagnet, there exist two spatially-separated sub-lattices with opposite magnetizations (thus total magnetization is Zero). However, within each sub-lattice, the electronic states can be 100% spin-polarized at the Fermi level, undisturbed by the other sub-lattice due to the spin annihilation effect (which is itself because these two sub-lattices are non-identical. As a result, you can have a system in which the total magnetization is zero but the charge carriers have a perfect spin polarization.
  • asked a question related to Magnetic Materials
Question
12 answers
Wavelength of light is an obvious factor, but this is not my point of question
Some specific questions are
  • What can be molecular/atomic level mechanism behind temperature and density dependence of refractive index?
  • refractive index is square root of product of relative (electric) permittivity and relative (magnetic) permeability of a medium. How a ceramic/glass/polymer structure can attain high relative permittivity (higher dielectric constant means more polar groups in polymers, more charge imbalance in ceramics) and high relative permeability (aromatic groups and ferromagnetic ligand centers in polymers, second one also for ceramics) without losing transparency?
  • how phase angle of complex permittivity and permeability of a medium depends upon its structure (e.g. factors mentioned above, bulk of chain and steric effect in polymers, photon propagation and phonon-mediated dipole oscillation of ceramics, chemical substitutions in ceramic structure)?
  • Why some atoms elevate refractive index of ceramics and some substituent groups elevate refractive index of polymers more than others? While atomic/ionic polarizability can be explained from fajan's rule and pearson's HSAB theory, and magnetic behaviors can be explained from magnetic spin, electronic configuration (and spin exchange between nearby atoms); have there been any comprehensive work combining all these aspects to predict refractive index elevation?
Relevant answer
Answer
The refractive index of polymers directly related to the polarizability and depends on the wavelength of light.
If a material is structurally isotropic, then it is optically isotropic, and a single refractive index typifies the refraction behavior.
In crystals and anisotropic materials, the refractive index takes different values along different principal axes, and the material is said to be doubly refracting.
The molecular weight of polymers affects their refractive index, but its effect is not significant. In some polymers, as the molecular weight increases, the refractive index increases. For example, for Poly(ethylene oxides), when the molecular weight change from 303 to 9523, the refractive index increases 0.8% (from 1.44592 to 1.45392). While, for polycarbonate, as the molecular weight increases (from 228 to 7196), the refractive index decreases 0.95% (from 1.6021 to 1.5868).
As a result, the relation between refractive index and structural and physical properties is complicated.
I have attached one text about refractive index of polymers. I hope it would be useful.
  • asked a question related to Magnetic Materials
Question
8 answers
Hi
My sample is hard magnetic/ soft magnetic material which is combined to form a nanocomposite magnetic material. However, vsm analysis shows smooth hysteresis loops on perpendicular applied field and kink-hysteresis loops on sample in parallel applied field. If we say that a good exchange coupling happened in within the sample, but why do it has different shape of hysteresis loop at different direction of applied field?
Thank you,
Relevant answer
Answer
Dear Atiqa,
as it already reported by Mohamed El Hafidi and Sam Parker , it is important to consider the anisotropy of the sample shape. If your film is very thin, then if it is magnetized in a perpendicular direction, a demagnetizing field acts opposite to the direction of the magnetization vector. Therefore, it must be taken into account along with the external magnetizing field. This field has a strength of 4pM in the Gaussian system. Thus, the form of a loop measured in the same material is affected by the geometry of the sample. In particular, simply changing its linear dimensions can lead to a sharp change in the appearance of the loop. For the effect of the object geometry on the shape of the hysteresis loop and about of the difficulties in hysteresis loop interpretation see, for example, in: Hysteresis in Magnetism, 1998_Chapter 1 by Giorgio Bertotti, (https://www.sciencedirect.com/science/article/pii/B9780120932702500593).
In addition, the presence of several magnetic phases in the material can lead to the occurrence of features on the magnetization curve. In this case, the kinks can correspond to the remagnetization of various phases.
Similar hysteresis loops can occur in composite systems if the magnetic particles themselves have an elongated or flat shape, and a texture occurs in the film due to special deposition conditions (for example, in the presence of a magnetic field or during oblique deposition).
Texture (and the additional induced anisotropy associated with it) can also occur in a composite material due to the orientation of the light axes of individual nanoparticles in the presence of external magnetic field.
Farzad Hosseini-nasab mentioned the influence of different types of anisotropy on the behavior of the material's magnetization curves. Thus, features of hysteresis loops also occur in nanoparticles themselves that have mixed forms of magnetic anisotropy: Journal of Applied Physics 112, 053915 (2012), doi.org/10.1063/1.4749799.
Another example of the appearance of kinks is given in the article by Z. Guo, Y. Zheng, K. Li, Z. Y. Liu, P. Luo, Y. Wu_Asymmetrically kinked hysteresis loops in exchange biased NiFe/IrMn rings // Journal of Applied Physics, 2004, DOI:10.1063/1.1690113. In this case, the latter appear in a system with a displaced hysteresis loop due to the so-called effects of exchange bias and exchange (unidirectional) anisotropy, which occur at the interface between the ferro- and antiferromagnetic phases
  • asked a question related to Magnetic Materials
Question
18 answers
What is the best medium to fill a spherical resonant cavity to greatly slow the electromagnetic propagation velocity between a magnetic material at the center and the conductive cavity walls, preferably with not much loss? If the wave fronts get slightly compressed that might be OK. I need to slow things down enough that an HF or VHF magnetic ferrite can be used without the 1/4 wave radius length of the cavity being too large for a lab bench. Are there any companies that make this kind of thing? If I need to make my own then what dielectric and magnetic materials or meta-materials can I use to affect the permittivity and permeability so as to slow the velocity, must not cost an arm and a leg. Thanks
Relevant answer
Answer
What for?
  • asked a question related to Magnetic Materials
Question
4 answers
I need help understanding the Magnetocaloric Effect. My understanding had been that based on the idea of conservation of entropy, if spin entropy decreases for the uncompensated electron spins then lattice entropy must increase so that entropy is conserved and so the magnetic material gets warmer.
My confusion is regarding magnetic materials with no or low Magnetocaloric Effect. If the material's uncompensated electron spins align so as to have lower entropy, then where does the entropy go so as to conserve entropy? If it went into the lattice vibrations then the material would get warmer and so the material would be classified as having a strong Magnetocaloric Effect.
If the entropy transfers to electronic states then there should be radiation from these changing electronic states but it ought to be higher frequency than the radiated heat emissions from lattice vibrations. The frequency would be lower for relatively massive nuclei vibrations as part of the lattice vibrating, so they would move relatively slower than the very low mass of electrons changing states. Electrons would have to move much more intensely in changing states to have the same heat energy of nuclei motions within lattice vibrations.
Besides spin states, electronic states and lattice vibrations, where else could the entropy disappear to?
Can there be a hidden increase in entropy among the compensated electron spins and among compensated proton and neutron spins, like a greater level of frustration or randomness among their unseen interactions with each other, I mean even while they are still considered as compensating each other?
Relevant answer
Answer
My background is more in engineering than solid state physics. Please say if my understanding is correct. If an external electromagnetic signal from far away stimulates the spins of a magnetic material to move from an isotropic state to being very aligned then if all uncompensated spins change more or less coherently then they should radiate their own electromagnetic signal more or less coherently also? So spin entropy decreases and a signal is radiated that is capable of performing work exterior to the magnetic material?
  • asked a question related to Magnetic Materials
Question
2 answers
Should we first relax the structure (Volume, cell shape and ions) with non magnetic ground state and then use ISPIN=2 for single point geometry calculation with the relaxed structure? Would this method give more stable ground state energy?
Relevant answer
Answer
It depends on the specifics of your system. If you're trying to do this for a compound with small local magnetic moments, then it may be a clever choice to first do the optimization using a non-magnetic setting and then complete it with a a fully spin-polarized one (ISPIN=2). On the other hand, if you're working on strongly correlated materials containing high spin-multiplicity elements such as 3d transition metals or rare-earth f-electron elements such as Sm, Eu or Gd, you may never get a converged solution using ISPIN=1. The reason is, such localized states want to follow Hund's exclusion rule which can't be fulfilled this setting. As a result, they keep fluctuating around the Fermi-level, leading to instabilities or even divergence in the SCF loop.
  • asked a question related to Magnetic Materials
Question
2 answers
Hi, I am looking for this book "introduction to magnetic material" by Cullity , how can I find it?
Relevant answer
Answer
Thank you kindly for your guidance.
  • asked a question related to Magnetic Materials
Question
6 answers
Hello everybody, thanks a lot for your help. There are magnetic materials which enjoy magnetic anisotropy, this can be caused by several factors, but it results in a so called "easy magnetic axis", this is, a direction in which it is easier to magnetize the material, fear enough. I would like to know if exist any material in which, given an easy magnetic axis, one direction of the axis is "easier" than the other one, this is , the axis itself presents an "easy sense" so to say. Any reference on the subject? Thank you very much again.
Relevant answer
Answer
should be the same, unless the system is "biased" for example by exchange bias
  • asked a question related to Magnetic Materials
Question
9 answers
I am dealing with an alloy of TbFe. We found the magnetic coercivity of about 4 T at 2 K. The Curie temperature was recorded at about 200 K. All these properties are observed at very low temperatures. Can anyone help and suggest possible applications for such material.
Relevant answer
Answer
Hi Shiv,
The remanence value is reasonable. Here is an article ( ) that compares the low temperature magnetic properties of magnets based on Pr2Fe14B and Nd2Fe14B. The Pr2Fe14B magnets are suitable for low temperature (< 77 K) applications mentioned by Amit. You may compare your properties with these magnets. There is another article https://www.nature.com/articles/nmat4248 you may want to see.
Raj
  • asked a question related to Magnetic Materials
Question
3 answers
I have been using the method published by Sun and Zeng in 2004
I was able to synthesise the seeds, but in the subsequent step (seeds+precursor), I had no particles after reflux, or at least no magnetic material (I have yet to do DLS/TEM). For the record, I flushed the system with argon and evacuated (x3), prior to raising the temperature. Maybe it needs some oxygen in there??
Relevant answer
Answer
I agree with the above answer. The preparation of ferrite nanoparticles doesn't require argon or nitrogen gasses.
  • asked a question related to Magnetic Materials
Question
4 answers
Actually I am working on a ferrite material. And I want to study the spin wave excitation in the material. Since the uniform FMR mode is considered as the lowest energy magnon, how I can analyse an FMR spectrum? What are the possible parameters that can be studied by FMR spectrum of my sample?
Relevant answer
Answer
There are two basic properties that you can learn from the FMR: (i) magnetic anisotropy and (ii) magnetic damping. However, to extract useful parameters that you can compare with values determined by other experimental approaches you have to take into account the geometry of your particular Experiment. Moreover, you have to know the magnetization of your sample from an Independent measurement such as VSM or SQUID magnetometry. I guess that you are working with thin films. In this case: For your analysis I suggest the paper from M. Farle providing a comprehensive introduction to FMR ( REPORTS ON PROGRESS IN PHYSICS Volume: 61 Issue: 7 Pages: 755-826 Published: JUL 1998 ).
If your samples are bulk samples the analysis will significantly depend on the shape of your samples.
  • asked a question related to Magnetic Materials
Question
2 answers
Suppose for a given magnetic material,
We know the M vs T behavior experimentally at a given magnetic field, say 500 Oe.
Can we find out theoretically the M vs T curve at other fields using any equation or fitting??
Relevant answer
Answer
Use Power law of fields. Eq (3) and (4) from this paper: https://www.nature.com/articles/s41467-018-05111-w
  • asked a question related to Magnetic Materials
Question
2 answers
I have got a publication in which the authors prepared BaFe12O19/CoFe2O4. But the amount / concentration used for preparing the metal nitrate solutions were not mentioned in the publication (except mentioning 'stoichiometric ratio')in Materials and methods section.
Please give your ideas about how to find the weight and concentration of the chemicals used in the synthesis from paper. Attaching the full paper with this question.
Reference:
Yang H, Liu M, Lin Y, Yang Y. Simultaneous enhancements of remanence and (BH) max in BaFe12O19/CoFe2O4 nanocomposite powders. Journal of Alloys and Compounds. 2015 May 15;631:335-9.
Relevant answer
Answer
For example the compound (BaFe12O19) Is composed of one mole of BaO plus 6 moles of Fe2O3 So you can calculate how many gram of BaO you need from its raw material that is Ba(NO3)2 in such case to prepare 100 ml solution contains 1 molar of BaO using the following equation Wt = (M* V * M.wt)/1000
where: Wt = weight of Ba(NO3)2 needed to prepare the one molar solution of BaO
M= Molarity needed for the solution
V= the volume in ml (Cm3) of the solution that is in this example = 100ml
M.Wt= Molecular weight of Ba(NO3)2 and it equals to 261.34
By applying in the equation Wt = (1* 100 * 261.34) / 1000
hence the weight needed from Ba(NO3)2 is equals to 26.34 gram .
By the same way you can calculate the weight of Fe2O3 from its raw material that is here Fe(NO3)3⋅9H2O but remember you will need to prepare 6 molar solution
because the ratio between BaO and Fe2O3 in the compound is 1 : 6 as explained above .
you can apply the above equation to prepare any concentrations of the solution for any compound.
Regards
  • asked a question related to Magnetic Materials
Question
1 answer
Hi, I am looking for a solution manual of this book "introduction to magnetic material" by Cullity , how can I find it?
Relevant answer
Answer
It is a good idea to contact the editorial and ask them for the professor materials
  • asked a question related to Magnetic Materials
Question
3 answers
Hi, how do you calculate energy product of a magnetic materials? It is using area under the curve at second quadrant of hysteresis loop? Or using equation of BHmax = (UoMr 2) /4..?
I find that the equation might be depends on the strong exchange/ weak exchange coupling. Can someone explain? Thank you.
Relevant answer
Answer
- The (BH)max product equals the area of the largest rectangle that can be inscribed under the 2nd quadrant of the normal hysteresis loop (B vs H).
- Because the product (B.H) represents the magnetic energy density stored at each point of the hysteresis loop; (BH)max can be found by plotting B.H for all the points inside the 2nd quadrant as function of the induction B. This curve will look like a parabola, and the (BH)max product will correspond to the vertex of this parabola.
Both methods are represented in this figure: https://commons.wikimedia.org/wiki/File:Magnetic_energy.png
- Finally, I think that the equation (BH)max = (u0Mr/2)2 only is valid when you have an ideally rectangular hysteresis loop; then, it only holds only when Mr is almost equal to Msat.
  • asked a question related to Magnetic Materials
Question
5 answers
The temperature at which FC and ZFC (MT curves) separate is called blocking temperature. What exactly does it signify? How can we distinguish between a ferromagnet and antiferromagnet after looking at the MT curves?
Relevant answer
Answer
The temperature at which the ZFC and FC processes are departing from each other is known as the irreversible temperature. The ZFC maxima is sometimes called as the blocking temperature of the system. But this way defining blocking temperature is not good. Better to looks at the negative temperature derivative of the ZFC-FC data to find the blocking temperature after fitting with the log-normal distribution. Fozia Aziz
  • asked a question related to Magnetic Materials
Question
18 answers
I wish to do DFT calculations and use the frozen phonon approach via Phonopy. Should I pay attention to the magnetic moments?
Sometimes, individual atoms in a crystal have different magnetic moments. Does this have any additional effect?
Relevant answer
Correct me if I'am wrong but, I don't think the magnetic moment of phonons could be a relevant part in the dispersion relations, or in another properties of phonons, like its density of states, etc...
Phonons, if the have a magnetic moment, this should be very tiny, since Phonons are quasiparticles of zero spin.
Regards !
  • asked a question related to Magnetic Materials
Question
4 answers
I would like to ask the phenomenon of spin orbit splitting in inorganic and organic materials. It occurs only in magnetic material or any general material can show this property. Actually, I am getting a tauc plot with two linear segments that shows two band transitions. But, this material has no mixed phase or phase transition in this XRD pattern, also it is not magnetic in nature. What could be the reason? is it related to spin orbit splitting?
Relevant answer
Answer
Thank you so much sir for your valuable comment. Is it possible that spin orbit splitting could be one of the reason for two linear segments in tauc plot ?
  • asked a question related to Magnetic Materials
Question
4 answers
I am interested to know what is the role of magnetic material(i.e. ferrites) in killing the bacteria than the non-magnetic material? how magnetic nanoparticles going to affect the bacteria?
Relevant answer
Answer
Magnetic field generated by low-frequency square wave is an alternating magnetic field with steep rise and fall that generates strong shock wave, resulting in changes in the diamagnetism of the heterotrophic bacteria and the electric dipole moment of proteins, so metabolism of the bacterial cell was impeded and the microbial was killed.
  • asked a question related to Magnetic Materials
Question
5 answers
Hello,
Can you please explain, what does an isotropic magnetic material mean ?
I thought it meant that the susceptibility tensor doesn't depend on the direction of the magnetic field, only on its norm.
In this case the magnetization M and the magnetic field H may ot be parallel ?
Am I wrong for thinking this ?
Thank you
Relevant answer
Answer
File added
  • asked a question related to Magnetic Materials
Question
3 answers
We are planning to grow high quality Cobalt films by the Plasma Assisted ALD, and would like to save some time on trying different precursors. Our first guess was CoCp2, but we heard that the quality of Co film grown with this precursor is irreproducible. Can anyone share their experience with this topic?
Relevant answer
Answer
See the review article: Cobalt Thin Films: Trends in Processing Technologies and Emerging Applications.
  • asked a question related to Magnetic Materials
Question
3 answers
The underlying physics behind quantization axes for the electrons spin has never really been clear to me. I saw the Pauli matrices in my quantum courses, but the definition of different principle axes seems arbitrary.
In the case of a magnetic material, or spins in the presence of a magnetic field, there is a clear axis along which to define the spin. But what about when there is no magnetic field?
For instance, in materials with strong spin-orbit coupling electron wavefunctions are mixed between up and down spin polarization. i.e. spin polarized states are not eigenstates. Furthermore, this paper about Berry curvature in SOC systems says, " it cannot be assumed that their local spin quantization axes are antiparallel, as the interactions with neighboring bands may affect the direction of quantization" (DOI: 10.1103/PhysRevB.72.085110)
But what does up and down mean in this context? Can quantization axes be defined differently depending on the properties of the band structure?
Relevant answer
Answer
Ryan, the RKKY or spin-orbit select one given orientation of the spins. For instance in spintronics there are spetial configurations for the giant magnetoresistance, etc There are many different techniques to get a majority of spins in one given direction besides the stable magnetism based mainly in Hund rules.
  • asked a question related to Magnetic Materials
Question
5 answers
I am running relax calculations for Ni in interstitial position of MgO using VASP. Since Ni is ferromagnetic, I expected a net non-zero magnetic moment because bulk Ni has a magnetic moment of 1.7 BM. But the resultant magnetic moment of the system came out to be 0 which seems a little odd because even though MgO is anti-ferromagnetic, I believe Ni should have some contribution towards the mangnetization but it doesn't seem like it. I don't understand if it is supposed to be like the way it is or there is some problem in my input specifications. PFA all the input files for the calculation.
Relevant answer
Answer
Vishal Hariharan I am sorry. I thought this was a surface calculation. In terms of Ni and O covalent interaction, some charge transfer from the neighboring O atoms is expected. Also O atoms displace towards the Ni atom that suggest the formation of multiple covalent bonds. Ni orbitals (specially 4s and d) interact strongly with O p orbitals, forming a bonding combination and an antibonding combination. The covalent interaction between Ni and O pushes the antibonding orbital in such a way to be unoccupied in both majority and minority spin channels. This will cause d and s-d hybrid orbitals to be fully occupied and eventually the net spin to vanish.
  • asked a question related to Magnetic Materials
Question
9 answers
How do you measure half metallic nature and the spin polarization of a ferromagnetic material?
Relevant answer
Answer
  • asked a question related to Magnetic Materials
Question
4 answers
Hi everyone,
It's known that the cutting process of electrical steel introduce additional iron loss. Research articles indicate that the increase of iron loss when steel is cut with CO2 laser is much higher than the case where the steel is cut by punching. I was wondering, if the trend is the same for Nd:YAG laser cutting ?
Relevant answer
Answer
Bekka Nassim Yes It will lost less than tool cutting
  • asked a question related to Magnetic Materials
Question
5 answers
I wish to know that does the concentration of magnetic material affect the Remanence (Br)
Relevant answer
Answer
Please see the reference below:
S. Vadivelan, N. Victor Jaya. Investigation of magnetic and structural properties of copper substituted barium ferrite powder particles via co-precipitation method. Results in Physics, 6, 2016, Pages 843-850. https://doi.org/10.1016/j.rinp.2016.07.013.
Best Regards
  • asked a question related to Magnetic Materials
Question
3 answers
In other word, the dimensions of a permanent magnet how determines its temperature working? In magnetic standard there is a working temperature which not only relate to the magnet material but also it depends on the magnet dimensions.
Relevant answer
Answer
Hi Mahmoud, I am not sure what scale of the "dimensions" you mean. If it is in small scale( um or nm), I say yes. The size of the materials matters since the permanent magnetism is usually so-called 3D long range ordered magnetic material. The magnetic blocking comes from the interaction between magnetic domains. The total interaction energy should be larger than the energy of thermal fluctuation energy then the magnetization can be remained (so-called blocking). Certain kind of material has a certain critical size, which is the smallest size of a single magnetic domain. If the sizes of the material is very small, that means it can contain only several domains, therefore, the interaction energy can be very small and not enough to remain the magnetization. If the size is smaller than the critical size, the magnetic material will act as a paramagnet one, this is so-called superparamagnetism, another story.
  • asked a question related to Magnetic Materials
Question
3 answers
I wish to start a project that uses powerful magnets to propel a bullet through at high speeds without using electricity. The design would include a barrel made of completely magnetic materials to eject a bullet out of the barrel at high speeds using neodymium magnets and magnetic bullets. I understand the forces between two powerful magnets made of neodymium is incredibly large even with a low amount of mass. Could the forces involve possibly create enough velocity to propel bullets at high speeds?
Relevant answer
Answer
You can actually represent this as a potential energy/kinetic energy problem. The potential energy between two magnets is converted to kinetic energy if they're allowed to "fall" together, and converted to a significant amount of heat if they actually impact. Now envision creating a vacuum lined tube going through a hole in a large neodymium magnet. Your neodymium "bullet" would sit in the tube and be released to accelerate towards the magnet, converting the potential energy of the magnetic pull into kinetic energy (velocity) as it passed through the magnet. However, as it passed through to the other side, the pull would reverse and it would slow down, converting all that KE back in to PE, until it stopped and fell back again and again. Assuming no friction, this would ideally continue forever, although in reality it won't since you've created an oscillating magnetic field which, oops, radiates EM waves and thus energy is lost as radiation!
Railguns use oscillating fields to apply attraction and repulsion at appropriate points in the trajectory of the projectile and accelerate it constantly. Basically they're just a linear electric motor. A magnet is not a motor. You have to alternate the fields somehow. Spinning a magnet might work if you did it right.
And BTW, before someone makes the connection between gravitational PE and magnetic PE and then asks, "So how does gravitational slingshotting work for the space program?!!", that's a transfer of angular momentum, not gravitational PE. The planet, Sun, etc. slows down slightly in order to accelerate the spacecraft. Spinning the "drive" magnet to first pull and then repel the magnetic projectile as it passed would require the same amount of energy to rotate the drive magnet that was imparted to the departing projectile.
  • asked a question related to Magnetic Materials
Question
2 answers
Dear Colleague,
We are looking for a high field torque magnetometer, that could aid in separating the paramagnetic and ferrimagnetic fabrics in rocks. Are there any particular models that you would recommend.
Thanks
Amar
Relevant answer
Answer
Dear Colleague,
for distinguishing paramagnetic and ferromagnetic contributions to your sample, a stray field sensing Magnetometer might give ambiguous results. Both contributions add to the magnetic Signal. In contrast, you may consider a Torsion oscillation Magnetometer, which Comes with high sensitivity. For this type of Magnetometer only those components contribute that have a mechanical coupling of magnetization and sample, i.e. a strong magnetic anisotropy. This is typical predominantly for ferromagnets, such as Magnetite. A description of this Magnetometer can be found in: U. Gradmann et al., Appl. Phys. 10, 219 (1976).
  • asked a question related to Magnetic Materials
Question
15 answers
I'm trying to implement a uncompensated spins FM/AFM interface in a bilayers system that presents the phenomenon of exchange bias in Mumax, following the standard of the article "Modeling compensated antiferromagnetic interfaces with MuMax", however, I'm not succeeding. To implement uncompensated spins on the FM/AFM interface, do I have to define one or two AFM regions in Mumax? I tried to freeze the AFM layer with the "frozenspins" command but it did not work, can anyone help me with this problem?
Thanks a lot.
Oreci.
Relevant answer
Answer
Dear Yogesh Kumar,
You have to build two regions on Mumax R1 and R2 with different parameters.
R1 will be a cylinder and R2 will be a cuboid. Something like:
R1: = SetGeom (Cylinder (100e-9, 20e9). Trans (0.0, z));
R2: = SetGeom (Cuboid (400e-9, 100e-9, 20e9). Trans (0.0, -z));
  • asked a question related to Magnetic Materials
Question
1 answer
in an AMR (Active Magnetic Regenerative cycle), please could you show me practically how the magnetic material matrix works both as a refrigerating medium and as a heat regenerating medium.
Relevant answer
Answer
Dear Gua,
You can try to see some old literature (research) papers and encyclopedia.
Definitely you will get the required on this topic.
Wish you good luck.
  • asked a question related to Magnetic Materials
Question
8 answers
these garphs are for BiFeO3. These measurements are of same material. BFO is doped with Gd at step of 0.025 and Sm=0.1 fixed in my composition. These are the curves for my material. nature of material means whether my material is moving towards ferro, ferri or paramagnetism.
Relevant answer
Answer
Dear Priyanka,
your question and graph make me wonder
-- what do you mean by "nature of magnetic material"
-- if all the curves shown are for the same material, why are the results so different?
None of the measurements displays Curie-Weiss behavior over the entire temperature range. It would have to be a straight line. You can fit a straight line to the lowest temperature range of each curve where a fit by a straight line is acceptable.
But what I would care about in the first place is whther (a) your rsmples are OK and (b) whether the measurements are of sufficient quality. The red curve, for example, is non-monotonous -- which cannot be correct.
  • asked a question related to Magnetic Materials
Question
6 answers
Is first order magnetic phase transition better than second order magnetic materials for magnetocaloric applications? Does magnetocaloric property depend on type of magnetic phase transition?
Relevant answer
Answer
Thermal hysteresis can be define as the separation between the heating and cooling curves of magnetization vs temperature graph. If any material exhibit thermal hysteresis then the change in entropy (and also change in adiabatic temperature) under heating and cooling condition will not match. Therefore, it will result in an irreversibility in MCE. For an efficient MCE device we need a material which exhibit reversible magnetocaloric properties
  • asked a question related to Magnetic Materials
Question
5 answers
Fe@C and Co@C nanomaterials are two kinds of magnetic materials, which can be used as electromagnetic wave absorption materials. However, in some conditions, the wave absorbing property of the nanoparticles is so low, the reflection loss even cannot reach -10 dB. Shall we talk about the key facters affect the absorption ability of carbon-coated iron/cobalt?
Relevant answer
Answer
Dear Mr. Tiejun Zhao,
a very good question. Yes, we have the problem of a cutt off diameter of a nanoparticle. After the rule from Gubotti we must have a diameter of a nanoparticle over a limit line of the critical diamater, only then we have a absorption and a magnetic effect.
Please read this paper. Only in german language so sorry.
Sincerely Yours
F. Gräbner
  • asked a question related to Magnetic Materials
Question
4 answers
Since the discovery of graphene in 2004, there's been a lot of developments in epitaxial growth of various 2D layered vdW materials, with recent advances in graphene and transition metal dichalcogenide growth. More recently, there's been a lot of interest in transition metal halides for their magnetic properties, prime examples being CrI3 (for its layer dependent ferromagnetism) and alpha-RuCl3 (for its proximate Kitaev Quantum Spin Liquid behaviors).
Is CVD growth of transition metal halides possible? I haven't found any in the literature at this point.
Relevant answer
Answer
I suggest PLD, Sputtering, and Thermal Evaporation. You need also high substrate temperature and choosing substrate with lattice constant matching. If you insiste to use CVD you must find available gases of Cr, Cl, or with suitable chemical expected reaction yields the desired product.
  • asked a question related to Magnetic Materials
Question
1 answer
  • As we know that TWs formation takes place due to cubic to low symmetry structural phase transition ( due to either by cation displacement or octahedra rotation or both), which minimize the total strain of low symmetry phase. If i consider, phase transition only due to octahedra rotation or tilting, how the TWs will form in this type of structure ? i want to visualize Tws formation by rotating the octahedra of unit cell (which is responsible for structural phase transition as well)?
Relevant answer
Answer
If you have the information from your cristal structure in a file such as a CIF, you could use VESTA program.
  • asked a question related to Magnetic Materials
Question
2 answers
We are developing a room temperature vacuum system to measure magneto-electric properties of epitaxial samples. This system will have its temperature accurately controlled using a high performance Peltier device and we aim to measure, among other things, the hall resistances of the sample very precisely using a nano-voltmeter.
The design of the vacuum chamber, the heat sinking and all other aspects are covered, we are only stuck with the actual sample connections. Here are a few key points in the design brief for such a sample connector:
  • The sample will be bonded to the sample holder which is connected to the sample stage. The sample pertains to the piece of wafer of our material, the sample holder is a piece which the material is bonded to and holds the electrical contacts and the sample stage is the socket in the chamber which makes contact to the wires for the measurement equipment.
  • The sample of material must be as close to the temperature of the copper surround as possible, preferably using an electrically insulating, and thermally conductive material as the base.
  • The header requires at least 8 contacts, preferably 12 or more.
  • The sample holder must be easily removable and replaceable, preferably readily available or easily manufactured.
  • The materials used must be vacuum safe.
  • Any metals must be copper, silver or gold to eliminate any significant thermal voltages. There must not be able tin, nickel or iron (and ofcs not cobalt).
  • Any other materials must be non-magnetic.
  • The temperature range of operation will be -30C to 100C at the extremes.
It seems like this sort of thing must have been done. Surely people have made thermal voltage measurements on magnetic materials in a vacuum before? no? If anyone has some ideas please let me know.
Thank you for reading and any feedback you may have.
Best wishes,
Stu
Relevant answer
Answer
Have you considered using a PPMS puck?
12 contacts, good thermal conduction, and easily adaptable to a measurement setup under vacuum.
  • asked a question related to Magnetic Materials
Question
4 answers
I am trying to simulate domain wall motion in nanowires. In [1] with the below mentioned parameters, the authors have simulated domain wall oscillation in a constricted nanowire. The constricted nano wire is designed by offsetting a portion of the nano-wire in transverse direction by 15 nm. I am trying to reproduce their result in mumax3. I have attached the image of the regions.
The material parameters are- saturation magnetization = 600e03 A/m^3 magnetic anisotropy energy = 1e05 J/m^3 exchange stiffness = 1.3e-11 J/m current density = 8.65e11 A/m^2 spin polarization of the applied current = 0.6 damping constant = 0.014 Polarized electric current is flowing along positive x-direction
MUMAX 3.9.1 Code
// The exchange length lex = {Aex/ (0.5*mu0*Msat^2)}^0.5
// In this model lex = 7.58 nm approx
// We are considering cell dimension 2nm X 2nm X 3nm
// Define gridsize & cellsize
Nx := 128
Ny := 64
Nz := 1
sizeX := 256e-9
sizeY := 128e-9
sizeZ := 3e-9
SetGridSize(Nx, Ny, Nz)
SetCellSize(sizeX/Nx, sizeY/Ny, sizeZ/Nz)
//Define geometry
struc1 := cuboid(100e-09,40e-09,3e-09).transl(-40e-09,0,0)
struc2 := cuboid(100e-09,40e-09,3e-09).transl(40e-09,-15e-09,0)
struc := struc1.add(struc2)
setgeom(struc)
//Define regions
defregion(1,struc)
save(regions)
//Define Material parameter
Msat.setregion(1,600e3) // Saturation Magnetization in A/m
Ku1.setregion(1,1e05) // 1st order uniaxial anisotropy constant in J/m^3
Aex.setregion(1,1.3e-11) // Exchange stiffness in J/m^3
alpha.setregion(1,0.014) // Landau-Lifshitz damping constant
//Define Initial Reduced Magnetization
m.setregion(1,twodomain(1,0,0, 1,1,0, -1,0,0))
//Save data and vector field
runtime := 1e-09
autosave(m.region(1),runtime/10)
tableautosave(runtime/10)
//Initialize excitation
J.setregion(1,vector(8.65e11,0,0)) // Current density vector in A/m^2
Pol.setregion(1,0.6) // Electrical current polarization
run(runtime)
I will be really thankful if you could help in this matter.
[1] Sbiaa, R., and M. Al Bahri. "Constricted nanowire with stabilized magnetic domain wall." Journal of Magnetism and Magnetic Materials 411 (2016): 113-115
Relevant answer
Answer
I have tried to reproduce Figure 4 of the article (if you can share it with me). I observed that it uses a time of 5ns, with 1ns you can not draw many conclusions. Attached is another file test2.mx3, the secret is to hit the values of the command "twodomain", I believe that you will be able to reproduce the data. But I'll caution you that most of the time when we try to reproduce OOMMF data for Mumax, it's inconsistent with results. Try to work with variations of the parameters in Mumax, maybe you get the expected result. Beware of the dimensions as they are key to achieving your goal, in your file was 180 nm:
// Define geometry
struc1: = cuboid (100e-9, 40e-9, 3e-9) .transl (-50e-9,0,0) // L = 200nm
struct: = cuboid (100e-9, 40e-9, 3e-9) .transl (50e-9, 35e-9,0) // L = 200nm
struc: = struc1.add (struc2)
setgeom (struc)
Hugs!!!
  • asked a question related to Magnetic Materials
Question
5 answers
In our SQUID VSM (Quantum Design MPMS 3), for Pd standard sample (298 K, 1 T) we observe an error of 1% which is within the limit as by QD instructions. But for Nickel standard (Ms = 54.9 emu, 1.5 T, 300 K) we observe an error of 9%. why could it be. is it because Pd has low moment and Ni has high. Also should we calibrate using Ni standard when we do high magnetic samples? Can someone kindly help/answer this query
Relevant answer
Answer
given that you are using Squid why not use a sphere of clean Pb( Lead) ?
It's perfect dia-magnetism ensures linearity with applied field up to the critical field ( for Pb)
Beit a Squid or a room temp VSM coil system , <=1% accuracy requires that you always use exactly the same shape and size test sample as your standard ( beit Pt , Pd or Pb). The problem is that off axis sensitivity varies a fair amount with the exact sample shape, especially with gradiometer coil systems (With the caveat that the sample size is NOT << coil volume) . It is fairly easy to quantify this by calculation , by invoking the reciprocity theorem That is to say you calculate the B field that would be obtained anywhere inside the sample volume ,if the pickup coil system were to carry a current . Integration of this hypothetical "field" over the sample volume will give you a measure of the sensitivity to a particular sample volume/shape , not just an on -axis, centered point.
  • asked a question related to Magnetic Materials
Question
4 answers
transmission effect on magnetic materials.
Relevant answer
Answer
FTIR data and XRD are two different characaterizations.
XRD reveal the phase information of the crystal lattice of the materials and FTIR disclose the specific vibration band such as stretching vibration, bending vibration of OH, CO bond etc present in the materials.
Magnetic measurment tells about either a sample ferromagnetic or paramagnetic.
You cant directly correlate all characterizations.
you may follow
  • asked a question related to Magnetic Materials
Question
6 answers
Hello,
The expression of the frequency-dependent complex magnetic susceptibility has a term, defined as the high frequency limit of magnetic susceptibility [1]. I was wondering what can be the physical meaning of the susceptibility at very high frequency. At very high frequency the particles should not be able to follow the applied magnetic field which should result in a zero susceptibility. Is there anything that is analogous to the high frequency limit of the
permittivity that is caused by the intramolecular distortion polarization?
[1] Fannin, P. C. "Investigating magnetic fluids by means of complex susceptibility measurements." Journal of magnetism and magnetic materials 258 (2003): 446-451.
Relevant answer
Answer
I absolutely agree with Daniel, I'm not going to argue or even make some recommendations for a specific system of researcher Partha Sarathi Paul.
And moreover, I do not consider myself competent enough for such judgments in General case.
  • asked a question related to Magnetic Materials
Question
6 answers
Looking for suppliers of HD or HDDR furnaces for magnetic material processing.
Relevant answer
Answer
Dear Sir, i know one supplier please refer if it is possible
  • asked a question related to Magnetic Materials
Question
2 answers
I see magnetic materials for use as directional couplers, isolators, gyrators, circulators, etc. but they never give the kind of spec.s like I need to see, for like an inductor core. I need to see spec.s with a chart of 2 separate curves, 1 for real permeability and 1 for imaginary permeability versus frequency in the GHz range. I need to find magnetic materials that have significant real permeability levels with low loss in the GHz range. I guess that means the imaginary permeability needs to not kick in until an even higher GHz range than the real permeability GHz range. Does anyone make and market such animals? Are there any trade magazines where I can find advertisers for such magnetic materials? Years ago I talked to the president of a materials company and he said his company had developed magnetic material with real permeability of 40 at 1GHz but today I still see no products like that on the market, not even from the guy who once told me they had created it . With all the advancements in nanomagnetic materials and molecular magnets I'd expect to see GHz range inductor cores more available. Any leads others can give me would be appreciated.
Relevant answer
Answer
Dear George
Excellent question and concern specially now-a-days. Though I was involved with magnetic materials but have been outside the applications for long now. My advise is to involve Dr. Jose Hejase [IBM] in the question maybe he or his colleagues could help here.
  • asked a question related to Magnetic Materials
Question
5 answers
Dear all, Has anyone here used the OVITO (http://ovito.org/index.php) program or the Rasmol (http://www.openrasmol.org/) program ???
I want to generate the example image of the site simulations: 
However I'm not getting success ... I use windows, if someone can help me I'll be grateful.
Relevant answer
Answer
Hello,
I have used Ovito under Linux, with no problems. Not only for creating static images, also for animated movies.
Perhaps you could explain some more what are the problems you are having?
Regards,
  • asked a question related to Magnetic Materials
Question
3 answers
I have used 2 time sputtering system in my lab for the deposition of CoFeB, after which I am not able to deposit any other material in the same system (MoO3, ZnO), also I am not able to tune the RF power with the matching network.
Relevant answer
Answer
The deposition of a magnetic material onto the inner walls of your deposition chamber (and perhaps onto other components that yoy may have inside, for instance a collimator chimney on top of the target, etc) may alter slightly the magnetron effect in your sputtering source. FeCoB takes many magnetic field lines and as a result the magnetron effect decreases. You can try to change the configuration and/or strenght of your magnets below the other targets (MoO3, ZnO) and also increase the gas Pressure.
  • asked a question related to Magnetic Materials
Question
1 answer
Hello, I'm a member of the Li Yongjian research team and our resarch directions is mainly about 3-D magnetic property measurement and magnetic material characterization. We also use LabVIEW to control the measurement process. I have seen your article whic intriduces a adapitive digital feedback, I'm curious about this control method that uses the difference of the target waveform and real waveform to modifiy the output signal. I tried to use your method to control the B. But there are some problems,I want to ask if your method is only applicable to ring sample where the H is calculated by Ampere's law?for in this case, H is linear with I. But our 2-D setup uses H coils to measurment H? Will this method also be okay?
Relevant answer
Answer
Hello, if I understand correctly the question, then Yes, for your setup, H will also linear with I. Only the proportionality factor will depend on the design of your coils.
  • asked a question related to Magnetic Materials
Question
22 answers
I have a target made with primarily Fe(Iron). I am trying to sputter it anyways. DC,Diode,Rf(which I don't think will work but still I am trying). One problem is that the target is quite thick(about 0.25inches) so we are trying to make it thinner but is there anything else to try except changing to high power magnetron gun? I would like to hear and read about your experiences with sputtering magnetic materials.
Relevant answer
Answer
Dear Bhuiyan,
Magnetic targets should be sputtered with a magnetron having first of all a very strong magnet array (NdFeB or Co4Sm magnets). In case of a planar magnetron, work with a magnetron having pole pieces sticking out NEXT to the target itself. You will have only a little contamination in the thin film from those pole pieces. DC sputtering is fine. Measure the magnet stray field parallel to the target surface about 1 mm above the target surface before you start any depositions (use a hand held probe for this). You will need a few 100 Gauss in order to keep a stable plasma. As Fe will hardly arc, it might be a good idea to start the deposition process with higher pressure (e.g. around 2.E-02 mbar and once a stable plasma is achieved, to lower the deposition pressure (to some 5E-03 mbar). But in any case 1/4 inch thickness for pure Fe is a lot (this is 6 mm). You might need to make the target thinner to below 5 mm (e.g. 4 mm) in order to get a decent stray field.
Paul
  • asked a question related to Magnetic Materials
Question
4 answers
I want to simulate a hysteresis loop using monte carlo simulation in any program, it can be Matlab, Maple or C ++, which routine should I implement?
  • asked a question related to Magnetic Materials
Question
6 answers
I want to simulate hysteresis loops using an expression similar to this one of the figure, I can already simulate using coherent rotation of the magnetization, however I have never worked with this type of Hamiltonian model ... can anyone help me write or give a hint how to implement it in Maple, Matlab, or other simulation program.
Thanks a lot.
Oreci.
Relevant answer
Answer
You can try a simple algorithm such as the Metropolis algorithm