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# Spintronics - Science topic

Explore the latest questions and answers in Spintronics, and find Spintronics experts.

Questions related to Spintronics

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.

Hello everyone, I am currently working on a Heusler alloy system which has a

**non-collinear**magnetic order as reported by a earlier study. I intend to further explore this non-collinear magnetic state. It would be really helpful if someone can suggest me some properties that can be investigated**theoretically**in order to see if it has a potential use in spintronics devices or if it has some kind of other applications. I am using VASP. Thank you.Dear all

what is the new and HOT promising diluted magnetic semiconductor materials, that can have ferromagnetic and semiconductor properties close to room temperature? Wich not very difficult to realize (based on typical crystal growth techniques, availability of source)

My question is directed for research purposes, not necessarily for commercial applications.

Please share your knowledge. Additionally, If you know a good paper for this question, please tell me.

Thank you in advance.

Best regards.

Ismail

Hi everyone, i'm a beginner with VASP and i have some trouble with my spin polarized relaxation,

in fact i try to relax a 2 x 2 x 2 BiCoO3 tetragonal supercell with different magnetic configuration.

It works well for some but it switchs to orthorhombic latice for others, and i don't know why since the symmetrie shoudn't be broken with Z oriented (by default) spins.

Did someone know how i can force the tetragonal cell while leaving a/c free ?

My INCAR for C-Type AFM :

SYSTEM = BiCoO3

NCORE= 4

PREC = accurate

ENCUT = 550

GGA = PE

LDAU = .TRUE.

LDAUTYPE = 2

LDAUL = -1 2 2 2 2 2 2 2 2 -1

LDAUU = 0 4 4 4 4 4 4 4 4 0

LDAUJ = 0 0 0 0 0 0 0 0 0 0

ISTART = 0

ICHARG = 2

INIWAV = 1

NELMDL = -9

LREAL = AUTO

ISYM = 2

AMIX = 0.4

ISMEAR = -5

LMAXMIX = 4

Ionic minimisation

NSW = 100

ISIF = 4

IBRION = 2

EDIFFG = -3E-2

POTIM = 0.5

ISPIN = 2

MAGMOM = 8*0 -5 -5 5 5 -5 -5 5 5 24*0

Electronic minimisation

ALGO = Fast

EDIFF = 1E-4

NELM = 60

LWAVE = .FALSE.

LCHARG = .TRUE.

Lattice parameter obtained :

7.4820927815601488 7.4261381663482009 9.4695336886550603

Thanks.

how to make thin film in simple way of magnetite material??

is there any practical for spintronics applications simulation?/

This is important today, as it is well-known that a shadow has fallen over the race to detect a new type of quantum particle, the Majorana fermion, that could power quantum computers.

The Nature retraction is a setback for Microsoft’s approach to quantum computing, as researchers continue to search for the exotic quantum states.

While the evidence of elusive Majorana particle dies --- computing hope lives on, and is now made possible by using tri-state+ [1] in software with standard binary hardware, while enabling the use of spintronic methods and other novel approaches using integers [2].

In that, it is useful to desconsider irrationals and infinitesimals, treating them as illusions, and clear the field.

The fact that many irrationals are in physics formulas, although non physical, is another motivation, to simplify. We then obtain new insights, such as a discrete spacetime, and a connection between quantum and GR -- that was already expected.

Mathematics cannot be independent, as all science is interrelated. What is your qualified opinion?

References

[1] Ed Gerck. Tri-State+ Communication Symmetry Using the Algebraic Approach. Computational Nanotechnology. 2021. Vol. 8. No. 3. Pp. 29–35. DOI: 10.33693/2313-223X-2021-8-3-29-35

[2] Ed Gerck. On the Physical Representation of Quantum Systems. Computational Nanotechnology. 2021. Vol. 8. No. 3. Pp. 13–18. DOI: 10.33693/2313-223X-2021-8-3-13-18. Change all occurrences of "Eq.(3)" to "Eq.(4)"

Magnetic Semiconductors, particularly in Spintronics, the spin of the electrons are considered that provides structures that allow for a dramatic reduction in energy consumption. Also, it is known that silicon causes electrons to lose their spin state. Hence, how can this control of the spin for long distances be conceivable?

Kindly share your views.

Thank you!

What material do you suggest to start experimenting on Spintronics and get familiar with this field?

Spin orbit torque (SOT) switching of ferromagnetic layer with perpendicular (Out-of-plane) magnetization requires an additional in-plane magnetic field along the direction of applied charge current.

Could any one please give a lucid explanation for the need of such in-plane magnetic field and also please explain symmetry of which is broken by this applied field?

I measured the AHE voltage of my hall bar device using a lock-in amplifier; I am a bit confused with the analysis of this data; I have checked in several papers that the y-axis (hall resistance axis ) is usually symmetric about the origin, what is the reason for this;

1.is the centroid of the hysteresis curve is subtracted from all the data, and then it is plotted against the magnetic field?

or

2. since the AHE resistance signal is directly proportional to Mz (z-component of magnetization), so do I have to change the sign of data when I change the voltage values to the resistance values from the point when switching is happening?

Unless there is some systematic error on the instrumentation used, I have observed an inverted peak when measuring the FMR absorption derivative for a YIG/NM/m-FM thin-film sample. The YIG layer was deposited via magnetron sputtering on GGG(111) substrate and is not monocrystalline but exhibits only a few crystalline phases. The observed anomalous peak is normal at lower frequencies, goes through a change at 2.5 GHz and becomes inverted at the higher range. Another peak observed for the same sample (probably corresponding to a different crystalline phase) is not inverted but at least four times more intense, both at lower and at higher frequencies. Both peaks occur on the same FMR dispersion curve.

Valleytronics can be realized by accessing different spins coupled with different valleys. In monolayer TMDs, time-reversal symmetry should be present while spatial symmetry should be broken to realize spin-valley polarization. People use a magnetic field to detect this spin-valley polarization. then why TRS is not broken on applying magnetic field?

In Co/Pt bilayer deposition, why it is that first, we have to deposit an underlayer (usually Tantalum) on Silicon substrate and then Pt, why, in general, Cobalt is not deposited on Silicon while preparing a Co/Pt bilayer?

Generally, linear polarized light helps in understanding the carrier dynamics, wheres circularly polarized light will revel the spin relaxation dynamics which is very much necessary for any kind of spintronics applications. I have found that people use achromatic quarter waveplates to do so. It will be really helpfull if anyone provides further necessary details like specification, position of this particular waveplates in TA set up etc.

Recently, the current induced magnetization switching by spin-orbit torque (SOT) using the basic spin Hall effect is identified as a vital ingredient for non-volatile spintronic memory and logic devices.

Spin-based devices such as magnonic chips, spin-torque oscillators mostly find their application in signal processing, computing, etc. Is there any research work focusing on developing magnonic and spintronic devices for medical science?

Velocity of the electron in the metal is ~ 10^6 m/S which is 1/300 the speed of light. So, If the electron's velocity is not relativistic, then how a moving electron in a material can experience an electric field as magnetic field in its rest frame and hence exhibits Spin-Orbit coupling. How can I understand this.

After growing the films of topological insulators, what are the measurements which can confirms the TI?

Most of papers show ARPES is one of the technique which can confirm the growth.

Can one confirm it by transport measurements? or any other measurements?

Thanks in Advance !

If I do MFM paramagnetic thin film patterned on SiO2, will it give a phase difference like ferromagnetic films?

Hi,

Basically, I aim to develop a one semester (6 -months) coursework on Magnetic Tunnel Junctions (MTJ).

I am able to find a lot of books on Spintronics with a few chapters on MTJ.

1) Can anybody suggest me a book that specially focuses on every aspect of magnetic tunnel junctions ( Basic introduction and priniciple, working of Magnetic tunnel junctions, theory of spin transfer torque in MTJ, experimental fabrication of MTJ - Materials as well as synthesis perspective, Heusler alloys in MTJ, Theoretical models for characterization of MTJ, Experimental characterization of MTJ).

OR

2) Can anybody suggest a book or two on Spintronics that focuses on MTJs.

How do you measure half metallic nature and the spin polarization of a ferromagnetic material?

Respected All!
May I know the importance of large band gap in half-metallic compound?
For example if Co2FeAl gives wider band gap in spin down as compared to Co2MnAl, what can be concluded? or What is the specialty of wider band gap compound over the low band gap one? Can we predict the efficiency of spin-injection or magnetic memory among these two compounds in terms of their spin band gap?

Hello dear researchers, I just started to learn about the valleytronics but its a quite complex to get in this subject. Can anybody give me some useful tricks? also can anybody elaborate in a simple words that what are the differences between the valleytronics and spintronics.

Alloys for example NiFe, CoNi, CoFeB are used in thin films with in-plane and perpendicular anisotropy.

Hello everyone, earlier I was using the Gaussian 03 and there I used to include the keyword IOP(5/33=3,3/33=1) to print the Hamiltonian and overlap matrix in output file. But, recently I have switched to Gaussian 09 and using the keywords IOP(5/33=3,3/33=1) in root section, though it prints the overlap matrix but gives null alpha and beta matrix. I also tried 'IOP(5/33=3.3/33=1) pop=full' but for no avail.

What keyword should I use so that it print the alpha and beta matrix?

What are the available tools for spintronic device simulation?

Need free software available for the simulation of spintronic devices like spin transistors and memory devices.

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.

At what field are the anomalous Hall conductivity and longitudinal conductivity calculated to determine mechanism (extrinsic or intrinsic or metallic conduction) for magnetism ?

The conductivity can be considered at zero magnetic field where the AHE conductivity is the residual, or at high magnetic field where the AHE conductivity saturates. The first approach makes more sense but there is no clear indication in literature about the field at which the conductivity were calculated. Thank You.

Do you know about some articles calculating the band structures of DMS containing Mn in general and number of holes in Mn 3d band in particular? I need this information to calculate magnetic moment from XMCD measurements. Many thanks in advance.

Dear all,

Confusion is always coming to me when I come across A-type/C-type/G-gype/E-type antiferromagntic arrangement. There is few references on the arrangement of antiferromagntism.

Can somebody help me to find the earlier reference which classified the antiferromagnetism or help me to differentiate this??

Anderson localization insulator can be induced by defect disorder, such as impurity atoms, atom vacancies and so on.

Does anyone know the limited concentration value of defect disorder (such as oxygen vacancies in Pr

_{0.7}Ca_{0.3}MnO_{3}) to make Anderson localization, or is there have some papers have studied this question?How to find the magnetic dead layer film thickness (for magnetic materials such as Co2MnSi, CoFeB,.. alloys) for ultra thin films by experimental method ?

From my EPR spectra, I could see that there is an increase in the derivative of the spectra as a function of doping it with Iron.I have observed from my previous results that there is an obvious formation of iron oxide separately from the main compound nickel oxide. But from this EPR spectra, I am not able to give a direct explanation on the spin-glass, ferromagnetic phase formation. How do I find the direct relation for the uncompensated spin from the spectra?

is it possible to have strong spin orbit coupled electronic motion in 3D??

**PRL 99, 236809 (2007)**

In the foregoing article link , I want to know how have they plotted figure 4 (a) in particular?

I just want to know how these two technologies are compatible to each other when we fabricate the STT-MRAM memories. One bit cell of STT MRAM consist of one MTJ + one NMOS transistor.

I define the geometry by atlas, uniaxial anisotropy, Magnetostatic energy and exchange interaction by oxs. I define the initial magnetization as

m0 { Oxs_RandomVectorField {

min_norm 1.0

max_norm 1.0

}}

but when I try to visualize the magnetization using Oxs_TimeDriver results 0. Why?

Thanks

I know that when spin is pumped from the FM layer under FMR, the angular momenta is transferred from FM layer to NM layer, which results in increase in damping constant as well as FMR linewidth in bilayer system.

I am curious to know the next steps

1. How the pumped spin results in linewidth broadening? I is it broader for metallic or insulating NM layer?

2. will there be no spin pumping if there is no carriers in the NM layer? on the other hand no linewidth broadnneing?:

3. I am not able to visualize these steps. Can someone please help me?

Normally in trilayer structure (Pinned / spacer (nonmagnetic metal) / free layer), status of the free layer was read by the analyser kept in the top of free layer. But in the pentalayer (Pinned layer 1 / spacer (nonmagnetic metal) / free layer / spacer(nonmagnetic metal) / Pinned layer 2), the additional pinned layer is kept above the free layer. Theoretically, we can easily study the magnetization switching by solving the dynamical equation. Experimentally, how can read the magnetization status of the free layer in the pentalayer structure?

Multilayered Ni / Ag structure was calculated using VASP. I would like to understand how to get from the results of the calculation the specific energy of atomic orbitals. That is, find what orbitals used to construct the total wave function of the quantum numbers and energy.

Researchers are very excited for TIs which show some unique properties such as spin momentum locking and large spin-orbit interaction. they say spins are 100% intrinsically polarized in TI.

I have one confusion. In TI spins transport in two opposite direction with one spin up and other spin down. then how will we get large spin polarization. because we have both spin up and spin down spins.

Please explain it

Thank you

I need a comprehensive device which can be used to take IV curves, Magnetosreistance, tunneling magnetoresistance and any other relevent technique for MRAM.The device should be cost-effective due to limited budgetary estimates (80,000 USD)

or Measurement of spintronics related characterizations.

When an electron passes thru a magnet (like in the Stern-Gerlach experiment) the projection of its spin changes. The biggest change is when the projection is perpendicular to the magnetic field. After the magnet the projection is parallel so it has undergone a 90 degree rotation. (this what I mean by something and hope that anyone would agree).

But now lets look at the energy of the electron. As the energy of the electron does not at all depend on the spin or its projection it follows that its energy hasn't change. It is no wonder as the magnetic field is known not to do work. But then the magnet and its field also doesn't change. That's what I call nothing.

So to summarize:

1. There was a change induced by a system (the magnet) and it hasn't change

2. A system (electron) has undergone a change and it was not connected with energy flow.

How is this possible - it seems to contradict physical laws?

We have take a trilayer nanopillar consists of two ferromagnetic layer separated by a nonmagnetic metal layer. Suppose if we consider ferromagnetic layers are align parallel(and aligned along easy axis, say X-axis) and ferromagnetic layers lies in XY-plane, then RKKY coupling arises due to the conduction electron reflection at the interface of the ferromagnetic layer. We can be express it interms of the coupling field. My doubt is, In which direction the coupling field will act (in which direction we express the magnetization in the field equation)?

P.S: I herewith attached the article having the expression for RKKY field.

I would like to know if you have two layers of ferromagnetic iron nanoparticles inside of conductive polymer matrix layer. Can Scanning Tunneling microscopy spectroscopy be used to observe GMR effect as a significant change in the electrical resistance depending on whether the magnetization of adjacent ferromagnetic layers are in a parallel or an antiparallel alignment. So just with applying magnetic field in STM equipment we can detect these changes? Is this feasible?

For example, to get answer, could we use classical formula (44.4) from the book Landau,Lifshitz "Theory of field" (see the attached photo) ?

It's because, we suppose, the distance between the electron of conductivity and the atom is equal approximately the distance between two neighbor atoms which can be in interval from R = 10^{-5} cm to R = 10^{-7} cm, whereas the radius of electron orbit is r = 10{-8} cm. Thus (see photo) R >> r. Just in that approximation the formula (44.4) was obtained.

Am I right?

What is magnetic field?

Thank you in advance.

I have to improve the tunnel spin polarization in our devices, however, I do not have MBE equipment. How can I induce a good tunneling barrier?

Hi everybody.

I'm looking for GPU-accelerated packages in DFT calculations, I wonder if anyone knows an accurate package which also supports GPU acceleration (except quantum-espresso), and how much speedup I can gain with gpu in dft calculations? Also I want to mention that my calculations are in spintronics.

Best Regards

Does anyone modeled STT-MRAM accurately and published papers..I see some, but if someone can share that would be great, thanks!

In TMR or Spin-Valve structure most of the cases Synthetic Antiferromagnetic layer (SAF) is been used as a reference or pinned layer. What advantages it provides over conventional layer consisting only AFM/FM exchange bias?

Non-locality is a curious feature, yet essentially a quantum attribute that is linked to the violation of Bell inequality of any form. It arises from the impossibility of simultaneous joint measurements of observables. The Clauser-Horne-Shimony-Holt (CHSH) inequality is the only extremal Bell inequality with two settings and two outcomes per site. This inequality provides a basis to compare predictions of quantum theories with those linked local realism.

During non-Markovian dynamics of open quantum systems, there is break down of the well known Markovian model. This may occur due to strong system-environment coupling or when un-factorized initial conditions exist between the system and environment. Notably, a statistical interpretation of the density matrix is not defined for non-Markovian evolution.

My question is: Is there increased non-locality when a system undergoes non-Markovian dynamics and if so, how can this be quantified. I used the word "increased" because non-locality may be present in the case of Markovian dynamics, and the query focusses on whether certain aspects of non-Markovian dynamics accentuates non-locality.

During reading of GMR, I slightly got confused. Some authors reveals that when spin up electron passes through parallel configuration (spin up) it is scattered while spin down electron passes without scattering.

Some shows that spin down electrons get scattered while the electron with parallel spin (spin up) does not get scattered.

What is the real mechanism?

Could anyone explain me?

I am attaching two figure taken from the literature.

Thanks

Could someone explain in simple way the difference between spin pumping and spin injection in spintronics?

Thanks !

I am trying to analyze the domain pattern of the demagnetized state of a ferromagnetic sample to obtain information regarding domain wall width and energy density. For that after demagnetization, I am trying to do a 2D FFT of the image pattern and obtain the amplitude of the FFT pattern. Can anyone suggest some literatures on how to use the FFT to obtain the useful parameters. My problem is that I do not know how to analyze the FFT pattern other than the formula of obtaining the domain wall energy density

I am trying to see if there are other methods than hall probe or NMR probe to measure magnetic fields.

Parity doublet means two orbital with opposite parities with different orbital angular momenta lies close to each other. Parity doublet is only seen in the case of largedeformed nuclei not in spherical nuclei. In spherical nuclei, these orbital is very far from each other.

In 1997, Ginocchio showed that the psedospin symmetry in nuclei is exactly conserved when the scalar potential S(r) and the vector potential V(r) have the same size but opposite spin i.e. sigma(r)=S(r)+V(r)=0. This discoveries not only reveals the origin of the pseudospin symmetry but also demostreted an unexpected succes of the RMF theory. The psedospin symmetries is much better for exotic nuclei with a highly diffused potential. In the case of pseudospin doublet , the energy levels spliting with two different orbital angular momenta but same angular momentum(j). In the pseudospin doublet is only persist in the case of deformed nuclei not in spherical nuclei . Can any body clear the difference between these parity doublet and pseudospin doublet. Is there same or different?

If (muSR) vs time is straight line with small slope what does that mean?

should we look Zero Field only or F ONE?

The rhombograms for the effective g-factors of Fe(III) allow to calculate these factors knowing the rhombicity E/D parameter and viceversa. But are there analytical formulas (perturbative for example) for these g-factors? In W. Hagen's book "Biomolecular EPR spectroscopy" it appears that there are not analytical formulas, except for low E/D ratios. If someone could point me to any bibliography where these are derived I would appreciate it.

I am a little confused with these two terminologies. It seems that both of them can show high resistance to perticular spin, so what is the difference between a spen filter and a spin valve?

As far my understanding tells, a BMP is a particular type of molecule-complex in an occupied donor or an acceptor. Bound electrons (holes) trapped by the defect states can couple with the available d/f shell ions within a hydrogenic Bohr orbit of radius rH (rH ~ 0.76 nm) and form BMP through the sp-d interaction leading to a net ferromagnetic alignment of the magnetic spins. Through the percolation of the BMPs, a long range FM ordering can occur in case of the materials like magnetic semiconducting material and other diluted magnetic materials where the concentrations of d-shell electrons and itinerant carriers are quite less as compared to the FM metals or their alloys.

Can anybody share detailed ideas on this regard, about the preferable conditions of BMP formation and their percolation to produce High temperature FM characteristics (like the required conditions of the donar/acceptor defect states, free carriers, concentration of d/f electrons, BMP concentration, order of magnetic moment etc.). Particularly, incase of 'Magnetic Semiconductor' materials.

I mean i have come across a few definitions and they all give me different results and I have gotten really confused over it and don't know which one to use.So I am awaiting for someone to come forward and clear the air over it for once and all.

There are many reports on defect related ferromagnetism in Oxide materials. Also its saturation moment is quite low and it varies a lot depending on the growth process. So is it possible to use it in the spintronic device applications in a controlled way?

In my experiment on spintronics oscillators I recorded Power Spectral Density (PSD)/Bandwidth as a function of frequency (using Spectrum Analyzer). I have corrected the background subtraction of our data. I considered data for I_dc = 0.0 mA as the background data. Moreover we have not used any preamplifier except the internal-preamplifier of the spectrum analyzer. As far as I know the gain of internal-preamplifier need not be corrected as it is automatically corrected being internal component of the Spectrum analyzer.For a particular dc current (I_dc), I added up all the PSDs at different frequencies and then calculated emitted microwave power of oscillator for constant (I_dc) by following formula:

Emitted Microwave Power = (Total PSD/Bandwidth) * Frequency range

Am I correct while calculating the emitted power?

Please give your comments.

Electrons have both charge and spin. Spin polarization is needed for a spin current.

I'm looking for some zero-moment half metals which have potential application in spintronic devices.

Your help is highly appreciative as I am looking to work on CPP-GMR devices.

Kindly tell me in detail about the possible outcomes of the "Anomalous Hall Effect" measurement.

I am trying to do RF sputtering for MgO at lowest possible pressure. With the same conditions (i.e. same power supply, chamber, base vaccum, cooling water, sputtering gun) I am seeing a consistent increase in the Lowest sputtering Pressrue for my MgO, I even recently ordered the same target from the same company to make sure it is not target degradation but did not help (the same as old target). I do not see this change for any other targets I have. I was wondering if anyone has any thought .

I am having problems with my samples showing not expected resistance. I do use photolithography to pattern them and ion etching to etch them (size of samples are about 50-200 microns, there are different sizes on the pattern) .from my resistance measurements, I only see very few (5-10%) of the samples are showing the expected values for resistance and the majority of them show very low resistance (and all almost the same value). I am wondering what is happening because the good samples are scattered almost randomly across the entire film and there is no correlation between their positions.