Questions related to Multiferroics
In doped multiferroic composites of BTO-CFO, i observed increase in dielectric constant by the application of magnetic field. However, in some cases, a decrease in dielectric constant was observed by applying magnetic field. Which factors may be responsible for such behavior?
We have measured the magnetic field dependence of the ordered magnetic moment of Tb and Mn in multiferroic TbMn2O5 by single crystal neutron diffraction. The Mn moment does not change significantly with magnetic field but Tb moment does. How can I calculate the expected field variation of Tb moment from crystal field effects?
For Polarization vs Electric filed loop measurement of multiferroic materials, is It necessary to make both top and bottom electrode of same materials..? and what will be the effect if both side electrodes are of same or different...
What is the reason of getting wide flattered loop like inclined horizontally...
What is the Difference in behavior of the characteristics curve of PE loop of pellets and thin films of same materials...
What affects the polarization value w.r.t electric fields in pellets, thick films and thin films of multiferroic materials ?
Generally for multiferroics sample pellets, we make metals surfaces on both side to make electrodes just like two parallel plates and measure the PE loop. But in case of PE loop of multiferroic thin films, if the area of electrodes of both sides of the film is different, then does the sample show the required characteristics loop?
Recent publications mention that the magnetic and ferroelectric phases in a multi ferroic material couple through the piezoelectric phase of the ferroelectric. How does that coupling occur if the dielectric is paraelectric and not ferroelectric? Also how would you measure the magnetodielectric coupling constant of a paraelectric/ferrite multiferroic material? Thanks
I want to know how we can relate magnetostriction with Applied magnetic field mathematically? Or if there is any way to derive it using mechanical equations?
I want to know during PLD, where from bound charges come at the surface of ferroelectric materials? I want to know their origin, their charge either positive or negative, and their screening process (i.e. how to screen) and their effect on polarization of material. Moreover I also want to know what is depolarizing filed and what is its origin and how it could effect ferroelectric materials? A good ferroelectric material should have high depolarization field or low and why?
The last thing I want to know that these bound charges/depolarization field could exist only in PLD film preparation or also can be in hydrothermal/solgel film synthesis ?
Kindly anyone who is expert explain it.
I am working on Multiferroics. In the course of my research, I have to etch SrTiO3 entirely (not only TiO2 terminated surface) during the process to fabricate hall bars. Most of the literatures I have gone through so far have not regarded SrTiO3 as principal layer, but as substrate. Can anyone please help me, based on their experience, how can I effectively etch SrTiO3 after lithography?
Thanks a lot
Abu Naushad Parvez
Research and development of lead-free piezoelectric materials are presently the hottest topics in the field of piezoelectricity. Also a huge advantage of PZT and related systems, is that this one family, with minor modifications, is suitable for nearly all applications.
Environmental and health issues related to Pb-based materials are obvious. According to RoHS, any homogeneous component containing more than 0.1 weight % of lead is subjected to restrictions ; and hence, the fact that the best piezoelectric materials contain lead up to 60 weight %, may in the future, seriously hamper their use in everyday applications.
my question is that "why people looking for replacement for PZT ( lead zirconat titanate ) which contain Pb up to 60% of weight because Pb is considered toxic or dangerous for life . While the alternative lead free piezoelectric KNN, BNT , BNN , BST , BT , BZT , all these alternatives also might contain toxic or hazard element for example Barium is toxic and dangerous for environment "
Why people want to replace lead? The alternative are toxic also? so why the replacement of hazard element with another hazard one ?
Doing the CASAXPS fitting software for Fe doped BaTiO3-xFe XPS data, it gives the At% . What is meant the atomic ratios of Fe2+:Fe3+ in a particular concentration of xFe in BaTiO3.
For me it comes around Fe2+:Fe3+ as 49:51. whether it may mean there is no creation of oxygen vacancy or it just simply gives the quantification of particular xFe in BaTiO3?
The coupling coefficient identifies the existence of two or more ordering in single phase. But how can I calculate and justify it?
Can any body provide any eBook link or reference paper related to this topic?
Science does not stand still. New opportunities for research keep appearing and, as a result, new findings and discoveries happen hand to hand with artifact discoveries. These discovery some time with considerable controversy in the literature, sometimes at unusually impoliteand unprofessional levels. Some time artifact discoveries also surprised the world of science.
1) Different groups presents different results on same material and trying to prove each other results as wrong. Is it not sicietificy sound if these groups exchange specimens before they claim the work of others is simply wrong?
2) In some cases materials have been considered to be with ground breaking discovery when the data can be interpreted more simply via other well-known mechanisms. Is it not import to look wider before claims a breakthrough discovery?
3) In some cases the experimental results are true, despite theory implying that this is not possible. Is it appropriate to reject a experimental output just because theory doesn't exits which can explain it?
4) Controversy and attention on a new anomalous phenomenon such as Room Temperature Superconductivity.
Ferromagnetic ordering breaks the time-reversal invariance irrespective of nature and type of ferromagnetic ordering. Does anti-ferromagnetic ordering also breaks the time-reversal invariance irrespective of nature and type or one can observed breaking of time-reversal symmetries in some AFM state (Like Neel State) and its preservation on other states?
In AFM state, is staggered magnetization only responsible for time revers symmetry breaking or any other intrinsic effect can also lead to time revers symmetry breaking?
In the ferromagnetic state, where the magnetic moments have spontaneously chosen to point in one particular direction, time reversal effect inverts the magnetization, so it would have a microscopically-observable effect. We thus say that ferromagnetism breaks time-reversal symmetry. What about AFM (M =0), is time-reversal symmetry broken in all case just because of change of sign of their staggered magnetization due to time reversal effect or time-revers symmetry breaking will depend upon type and nature of AFM state.
I have deposited the polycrystalline thin film of BiFeO3 multiferroic thin film using Pulsed laser deposition. XRD curve depicts the (100), (200) and (110) orientations.
A transition from ferromagnetic structure to flat spiral structure was observed in a groups of transition metal alloys. The space group is Pnma and the magnetic Mn atoms occupy 4c position. How to understand the occurrence of spiral structure in such compounds?
It is know that Dzyaloshinskii-Moriya interaction due to spin-orbit coupling is responsible for the spiral structure in some multiferroics oxides. However, this interaction just occur in the sample without centrosymmetry. In my sample, the Pnma structure is centrosymmetric, and this interaction cannot occurs. Is there some other interactions or models to explain the spiral magnetic structure in centrosymmetric transition metal alloys?
For transition metal alloys, the interaction should be itinerant or direct interaction?
Sometimes, the electrons localize and delocalized partially. In this case, should the interaction be RKKY?
We have acquired FMR curves dI/dH=f(H) for Fe3O4 superparamagnetic nanoparticles. I need to calculate their effective magnetic anisotropy Keff. How is this possible? Thanks in advance
please share the role and applications of magneto-dielectric effect in a multiferroic material. is there any possibility to verify the energy storage capacity using magneto-dielectric effect instead of P -E loop.
Thanks in advance
In case of Multiferroic Perovskite materials, the Current-voltage curves sometimes don't pass through origin and show diode type characteristics due to polarization. But in illumination condition, i have observed that with the interaction of photons some materials show lower current value than dark condition. What would be the physical significance of giving low current value?
Both multiferroics and super-capacitors are separately the area of interest in current era. Is their any way for multiferroics to be used in super-capacitors for any purpose ?
We know multiferroic property is the combination of the at least two ferroic properties among- (anti)ferromagnetic, ferroelectric and ferroelastic. In multiferroics, electric field controls magnetization as a result magnetoelectric coupling is found in that materials. How do this coupling originate? Is there any references?
Apart from ferroelctric photovoltaic effect, the multiferroic materials is enhance the power conversion efficiency, like a magnetic or ferroelastic materials. why? and how?
i am working on BiFeO3 multiferroics where Sm and Gd are doped at Bi -site and Sm=0.1 fixed while Gd varied at step of 0.025. Magnetic properties are continuously increases while Dielectric and microstrain shows zig-zag pattern. plz provide suitable answer.
Which aqueous medium is the best for stable and homogeneous DISPERSION of ceramic (PbTiO3) particles for TEM sample preparation ? if particle size is in 500 nm range what precautions must be follow?
I have prepared Y2NiMNO6 nanoparticle and did magnetic measurements. From M-T , it follows as literature,i.e , ferromagnetic below 70 K , and paramagnetic above 70K but but surprisingly from M-H plot at 300 K , the plot look like paramagnetic but it has certain coercivity. Can anyone explain what could be the reasons behind it?
I am attaching the plots.
Is it possible to observe the ferroelectric domain through FESEM or HRTEM? how the magnetic domain will be observed. what about MFM magnetic force microscopy?
The figure shows σac (T) curves for the samples Bi1-xSmxFeO3 (x = 0; 0.05; 0.1; 0.15; 0.2) at a frequency of 1 MHz. How can we explain the displacement of the conductivity curves for substituted samples in the region of lower temperatures in comparison with the initial BiFeO3. What can be associated with a strong increase in conductivity near 300oC?
Thanks in advance for your comments!
In recent study of different spintronics system, people are studied that the ferroelectricity in type-II mutiferroics is produced by spin current. I want to know to clear the origin of spin current and how it produced the ferroelectricity in the type-II mutiferroic systems at the magnetic ordering point.
I performed experiment of a multiferroic system (BiFeO3). I got different curves but how should I know which one is correct
The room temperature M-H curve shows ferromagnetic behaviour. I need to fit that M-H curve with the equation 2 given in picture to fin out the ferromagnetic component of the sample.Can anyone please provide the step by step procedure for fitting in origin or excel?
I need to correlate the ionic state of Fe with the magnetic properties of Fe doped ferroelectric material. My way of synthesis is solid state reaction method.can I correlate the reason for magnetic properties of that ferroelectric material by taking core level spectra of Fe 2p and parent material site Ti? through XPS we do only surface characterization so is it useful or not? Can we confirm the incorporation of Fe ion in the parent Ti site through shifting of Ti corresponding BE peaks?
How can we detect ferroelectricity in a material? Or better to say : How to prove whether a material is ferroelectric or not?
Observing a peak in "Dielectric Constant vs Temperature" graph is enough or this is just a necessity?
I need to study a good review paper on "multiferroics" (published recently) specially with a short explanation of the reason of ferroelectricity in each case. Better to say, I need to gain a general picture of achievements on this field up to now.
Thanks in advance.
I want to detect the band gap narrowing in Fe doped BTO(BaTiO3) through valence band XPS (VBXPS) characterization. The operator is asking which element do you want to detect in BaTiO3 for VB XPS? I didn't understand that because for the whole structure of Fe doped BaTiO3 we have one band gap along with impurity band gap. Can anyone please suggest the initial steps we need to consider before VB XPS spectra has to do?
How to find out the fermi energy for any ferroelectric material to give the binding energy range for the analysis?
Please suggest books for XPS and valence band XPS.
Hello everyone. I wonder if anyone can help me with this issue, or even a better understanding of it.
I make deposits of BiFeO3 thin films (100 nm) using a polycristalline BiFeO3 target. The technique used is RF magnetron sputtering.
As you may know, BFO needs annealing to reach the multiferroic desired phase. By using XRD diffraction, the initial post-deposit state seems to affect the post annealing result. The first two deposits I make, each of 40 mins long sputtering one after another, are identical, and reproducible each day. However the third sample I try to make, also for 40 mins long after the first two, is not even close to the first two. This is also reproducible each day. I tried resting the target from plasma heating for an hour between each sample deposit, but the results were not any better.
Thank you in advance for any answer.
In some ferrite -ferroelectric composites sometimes jumps are visible in some ferrite -ferroelectric composite sample, but not for all kind of compounds. What may be the possible reason?
This question is motivated by theroetical investigation we have done, trying to highlight ME coupling in some known Multiferroics. Indeed, despite carefull considerations of symmetry and considering the usual paths that such phenomenon should follow namely, magnetic field induced atomic displacement (triggered by Spin-Orbit Coupling in the structure), we could not show any measurable ferroelectric component resulting from applied magnetic fields (in our ab initio calculations). Experimentally, this is clearly observed for materials such as Magnesium Oxide (MgO) by the difference between ferroelectric Hysteresis different from the applied magnetic field and no Mag. field cases.
I am going to study the dielectrics properties of materials (ceramics ). since I am new to this area so can someone suggest me some best books on dielectrics..!! like B.D cullity , Stephen Blundell for magnetism..!!
I want to understand the basics of multiferroic materials. I am in my 2nd year of under-graduation. I am doing a project entitled 'Characterisation and fabrication of thin films of gallium ferrite'.
I want to understand from basics, what is the magnetoelectric coupling, how is memory stored using this coupling.
Basically I want to know the physics behind this multiferroicity.
All known EM antennas contain electrical current inside at radiation. What if someone mixes together dynamic electric field generated near ferroelectric piece and dynamic magnetic field near a ferrite? May EM wave be created at some angle and phase shift between the fields? Analogous method may be applied using a piece of 1-type multiferroic (inside it).
I am looking at confirming the presence of magnetoelectric coupling in doped-BTO thin films. I have confirmed the presence of ferroelectricity and ferromagnetism independently using the triangular waveform voltage and SQUID magnetometry.
To confirm the magnetoelectric effect, all I need to do is perform standard C-V measurements, with and without a magnetic field, and note any change in capacitance, according to the linked journal.
I have the capacity to perform C-V measurements using a Keithy semiconducter analyser, however I don't have the ability to performing the probing with and without the magnetic field.
Can anyone recommend how to best perform these measurements? Is there a probing station capable of performing these measurements, or is there an affordable way to make my own DIY probing apparatus?
Pervoskite based photovoltaic devices are similar to light dependent resistors. It does not generate current as in the case of conventional semiconductor based solar cells. Any Comments on this?
Analysis type (i) at Room Temperature, type (ii) at Low Temperature and type (iii) at High Temperature. Which one to prefer? (or) Does it depend on the application of sample?
Can we simulate M-H or P-E loops if we give the composition of the multiferroic as input or can we model them?
I have multiferroic TbFeO3 poly crystalline sample. I have put silver paste on both sides of the rectangular sample and baked at 1000 C for 1 hour. I have made I+, V+ contacts on one side of the sample and I-, V- on one side of the sample. The sample dimensions are: length = 6.4 mm, breadth = 4.1 mm and thickness = 1.47 mm.
I am measuring capacitance using LCR meter which is remotely controlled by LabVIEW program. I have put the sample in PPMS chamber and controlling both PPMS and LCR meter using LabVIEW program. The program is not showing any error and measurement is going smooth.
I am wondering why am I getting capacitance value of the sample as an oscillating wave?
Here I have used AC voltage level = 2.5 V (ALC ON)
Bias voltage = 1 V, AC frequency = 5 kHz.
I am doing PFM domain imaging of BiFeO3 sample.. I want to know how to do precicely calculatind the percentage of 71, 109, 180 degree domains in the system. If any one can give suggestions... wil be helpful... thank you
I have to perform a high pressure X-ray absorption measurements on bismuth based sample at APS synchrotron beam line. I don't know how to load the sample inside the diamond anvil cell for XAS measurements.
I am looking at performing ferromagnetic measurements of thin films using a Vibrating Sample Magnetometer. As my department does not possess one, I am having to travel quite a distance to use one, so I wish to familiarise myself with the processes as much as possible before hand.
I am familiar with the basic concept of how VSM measures the magnetic moment of the sample using the induced current in the pickup coils, however, I am unfamiliar with how it specifically measures Ferromagnetism. Also I have not had much luck finding comprehensive literature covering the measurements specifically of thin films samples. I have read that they are limited to a thickness of 50nm, but have been unable to find a reason why.
If anyone could provide any answers to the above queries, or links to any detailed literature who those new to the field of VSM, I would be extremely grateful.
I'm working on the canted antiferromagnetic multiferroic materials like BFO, DMO thin films. If i want to know the individual spin orientation on the surface of the thin films, whether it is compensated or not, defects at the surface, roughness induced change in spin configuration etc, please suggest me the techniques which can be used to do the same... thank you??
Dielectric constant was measured in sintered pellets of the compound with silver paste as electrodes using a Wayne-Kerr impedance analyzer. Note that the tan d peaks correspond to the points where k crosses the ordinate. What could be the explanation for this phenomenon? Contacts were ohmic as evidenced by same current in both forward and reverse applied voltages.
I am just starting out with rietveld refinement. I have been trying to get a good fit for my data of the compounds Bi0.8La0.2Fe(1-x)Zrx using the software Fullprof. But in all my 4 compositions (x=0,0.02,0.05 and 0.1) there seem to be some intensity mismatch of the structural model and observed data. I am attaching the pcr file for the composition Bi0.8La0.2Fe0.98Zr0.02 and also the starting structural model. A picture showing the fit of the data is also attached. As can be seen, the peaks around 2theta = 22, 46 etc. show positive deviation (calculated value is higher) while some peaks have lower calculated value. My obtained chi^2=9.2. How can I improve the fitting ? I am thinking preferred orientation is not the cause since the same trend is seen in all four of my samples.
I am investigating the multiferroic properties of doped Bi4Ti3O12 thin films on platinum coated silicon substrates. As part of my investigation, I am looking at minimising the film thickness. One of my initial experiments on thickness control involved using cross sectional SEM to measure the film thickness of samples deposited for different time periods, but otherwise processed using an identical methodology. Samples deposited for 1 hour, 2 hour, 3 hours and 3hours and 18mins(control sample) all show ideal grain flat grain boundaries between the BTO and platinum, and also the platinum, titanium oxide and silicon. However the thinnest sample, deposited for only 30 mins, shows a roughened substrate, as seen in figure 1.
At first, I believed this may be due to damage when the sample was cleaved in half, but another phenomena occurred later.
To investigate the electrical properties dependence on thickness, I fabricated thin 4 films using the same process again, with deposition time controlling thickness. The films were 50nm (24mins), 100nm(49mins), 200nm(98mins) and 380(186mins) thick . Gold contacts were sputtered onto the BTO surface, so electrical contact could be made between to the top and bottom of the film by placing probes on the Au and exposed Platinum substrate.
As seen in figure 2, an almost linear relationship can be seen between 100nm and 380nm, however a huge drop can be seen in the 50nm Sample.
A drop in capacitance could be explained by an increase dielectric contribution between surface states, but roughening of the substrate as seen earlier could also affect the crystallinity of the film.
I plan to performing cross sectional measurements to confirm the roughening, but am still unable to explain this why this occurs. Could anyone explain why the Platinum films roughens specifically when a thinner film is deposited on it?
From the temperature dependent dielectric measurement of a multiferroic material we observe a dielectric anomaly around 520 K, which is actually close to the antiferromagnetic Neel temperature. The frequency was 200 kHz. However, from DSC measurement we observed a transition at around 570 K (exothermic reaction). The heating rate was 10 degree C per min. Can anybody please give me any clue why in DSC measurement the transition was observed at higher temperature or why dielectric anomaly was observed at lower temperature? Thank you very much in advance.
From the temperature dependent dielectric measurement of a multiferroic material we observe a dielectric anomaly around 520 K, which is actually around the antiferromagnetic Neel temperature. The frequency was 200 kHz. However, from DSC measurement we observed a transition at around 570 K (exothermic reaction). The heating rate was 10 degree C per min. Can anybody please give me any clue why in DSC measurement the transition was observed at higher temperature or why dielectric anomaly was observed at lower temperature? Thank you very much in advance.
i am using keithley 238 with probe station to measure the i-v charactereristics of a ferroelectric thin film.
Is it possible to correlate the ferroelectric properties of a thin film by using i-v analysis..?
is it possible to quantify the same ?
how can i convert current in to polarization ? (by means of some integration method i heard)
thank you in advance....
I need to simulate piezomagnetic, piezoelectric and optical response of a composite multiferroic material to an applied electric field. Which COMSOL modules do I need?
I study the ferroelectric photovoltaic using the Bi2FeCrO6 material.
Bi2FeCrO6 is multiferroic material with ferroelectric and ferromagnetic properties.
Ferromagnetic properties is result from antiferromagnetic exchange coupling.
Due to the difference of the magnetic moment between Fe-Oxygen, Cr-Oxygen, Bi2FeCrO6 have the net magnetic moment.
Compared with BiFeO3, because of the ferromagnetic properties of Bi2FeCrO6, band gap of Bi2FeCrO6 is smaller than that of BiFeO3.
So, Photovoltaics using the Bi2FeCrO6 has better properties.
Can you explain why ferromagnetic properties make band gap smaller?
As we know that materials having more than one order parameters are called multiferroics. For ferromagnetic materials it is "spontaneous magnetization". Like this what is the order parameter for ferrotoroidic materials.