Tunnel magnetoresistance effect and magnetic damping in half-metallic Heusler alloys

Oogane, Mikihiko; Mizukami, Shigemi

doi:10.1098/rsta.2011.0011

Cited by 23 publications

(16 citation statements)

References 52 publications

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“…In experiments also a minimum at the concentration of Fe of x ∼ 0.4 is present, while such minima is not seen in the present calculations. However, similar trends as those reported here (for LSDA and GGA) are seen in the work by Oogane and Mizukami 15 . A possible reason behind the discrepancy between theory and experiment, could stem from the fact that as the Fe concentration increases, correlation effects also increase in relative importance.…”

Section: Effects Of Substitutional Disordersupporting

confidence: 56%

“…Many Heusler alloys have also been predicted to be half-metallic, in particular Co 2 MnSi has been the focus of many theoretical and experimental works 7,11,12 , due to its large Curie temperature of 985 K 13 , half-metallicity and low damping parameter, which makes it an ideal candidate for possible spintronic applications. Despite the large amount of research devoted to the half-metallic Heusler alloys, such as Co 2 MnSi, only recently theoretical predictions of the Gilbert damping parameter have been made for some Heusler alloys 14,15 . In the present work first principle calculations of the full Heusler families Co 2 MnZ, Co 2 FeZ and Mn 2 VZ with Z = (Al, Si, Ga, Ge) are performed, with special emphasis on the determination of the Gilbert damping and the interatomic exchange interactions.…”

Section: Introductionmentioning

confidence: 99%

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First-principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys

et al. 2016

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Heusler alloys have been intensively studied due to the wide variety of properties that they exhibit. One of these properties is of particular interest for technological applications, i.e. the fact that some Heusler alloys are half-metallic. In the following, a systematic study of the magnetic properties of three different Heusler families Co2MnZ, Co2FeZ and Mn2VZ with Z = (Al, Si, Ga, Ge) is performed. A key aspect is the determination of the Gilbert damping from first principles calculations, with special focus on the role played by different approximations, the effect that substitutional disorder and temperature effects. Heisenberg exchange interactions and critical temperature for the alloys are also calculated as well as magnon dispersion relations for representative systems, the ferromagnetic Co2FeSi and the ferrimagnetic Mn2VAl. Correlations effects beyond standard density-functional theory are treated using both the local spin density approximation including the Hubbard U and the local spin density approximation plus dynamical mean field theory approximation, which allows to determine if dynamical self-energy corrections can remedy some of the inconsistencies which were previously reported for these alloys.

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Section: Effects Of Substitutional Disordersupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

First-principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys

et al. 2016

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“…The damping parameter determines the length scales over which spin waves can propagate, the critical current density for STT excitation [91][92][93] and the fidelity of communication and data processing devices that exploit the resonant mode spectrum. Reduced damping parameters of a = 0.001 have been realized in half-metallic materials [94,95], where spin-flip scattering is thought to be suppressed, while V doping has been observed to reduce the damping parameter of the highest quality Fe films [96]. Therefore, future spintronic devices may be constructed from epitaxial thin-film materials, as in the semiconductor industry today, which also provide opportunities to more fully control and exploit magnetic anisotropy.…”

Section: Further Investigation and Exploitation Of Magnetization Dynamentioning

confidence: 99%

Ultrafast magnetization dynamics of spintronic nanostructures

Keatley

Kruglyak

Gangmei

et al. 2011

Phil. Trans. R. Soc. A.

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The ultrafast (sub-nanosecond) magnetization dynamics of ferromagnetic thin films and elements that find application in spintronic devices is reviewed. The major advances in the understanding of magnetization dynamics in the two decades since the discovery of giant magnetoresistance and the prediction of spin-transfer torque are discussed, along with the plethora of new experimental techniques developed to make measurements on shorter length and time scales. Particular consideration is given to time-resolved measurements of the magneto-optical Kerr effect, and it is shown how a succession of studies performed with this technique has led to an improved understanding of the dynamics of nanoscale magnets. The dynamics can be surprisingly rich and complicated, with the latest studies of individual nanoscale elements showing that the dependence of the resonant mode spectrum upon the physical structure is still not well understood. Finally, the article surveys the prospects for development of high-frequency spintronic devices and highlights areas in which further study of fundamental properties will be required within the coming decade.

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“…12 In particular, the half metallic properties of Heusler compounds can still improve MTJ switching efficiency through suppression of the interband scattering contribution of the Gilbert damping. 36,37 Moreover, the high spin polarization of MTJs using Heusler electrodes will also be useful in improving the TMR. Additionally, consistent with conventional ferromagnetic metal based MTJs, we find that the STT stays finite and large even when the TMR is suppressed with bias voltage.…”

Section: -mentioning

confidence: 99%

Bias dependence of spin transfer torque in Co2MnSi Heusler alloy based magnetic tunnel junctions

Zhang

Phung

Pushp

et al. 2017

Applied Physics Letters

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Heusler compounds are of interest as electrode materials for use in magnetic tunnel junctions (MTJs) due to their half metallic character, which leads to 100% spin polarization and high tunneling magnetoresistance. Most work to date has focused on the improvements to tunneling magnetoresistance that can stem from the use of Heusler electrodes, while there is much less work investigating the influence of Heusler electrodes on the spin transfer torque properties of MTJs. Here, we investigate the bias dependence of the anti-damping like and field-like spin transfer torque components in both symmetric (Co2MnSi/MgO/Co2MnSi) and asymmetric (Co2MnSi/MgO/CoFe) structure Heusler based MTJs using spin transfer torque ferromagnetic resonance. We find that while the damping like torque is linear with respect to bias for both MTJ structures, the asymmetric MTJ structure has an additional linear component to the ordinarily quadratic field like torque bias dependence and that these results can be accounted for by a free electron tunneling model. Furthermore, our results suggest that the low damping and low saturation magnetization properties of Heusler alloys are more likely to lead significant improvements to spin torque switching efficiency rather than their half metallic character.

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Tunnel magnetoresistance effect and magnetic damping in half-metallic Heusler alloys

Cited by 23 publications

References 52 publications

First-principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys

First-principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys

Ultrafast magnetization dynamics of spintronic nanostructures

Bias dependence of spin transfer torque in Co2MnSi Heusler alloy based magnetic tunnel junctions

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