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Title: Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect

Abstract

To search for half-metallic materials for spintronic applications, instead of using an expensive trial-and-error experimental scheme, it is more efficient to use first-principles calculations to design materials first, and then grow them. In particular, using a priori information of the structural stability and the effect of the spin–orbit interaction (SOI) enables experimentalists to focus on favorable properties that make growing half-metals easier. We suggest that using acoustic phonon spectra is the best way to address the stability of promising half-metallic materials. Additionally, by carrying out accurate first-principles calculations, we propose two criteria for neglecting the SOI so the half-metallicity persists. As a result, based on the mechanical stability and the negligible SOI, we identified two half-metals, β-LiCrAs and β-LiMnSi, as promising half-Heusler alloys worth growing.

Authors:
 [1]; ORCiD logo [2];  [3];  [4];  [5];  [6];  [7]; ORCiD logo [8]
  1. Nanjing Univ., Nanjing (China); Univ. of California, Davis, CA (United States)
  2. Univ. of California, Davis, CA (United States); LeapYear Technologies, Berkeley, CA (United States)
  3. Univ. of California, Davis, CA (United States); Donghua Univ., Shanghai (China)
  4. Donghua Univ., Shanghai (China)
  5. Univ. of California, Davis, CA (United States)
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  7. Nanjing Univ., Nanjing (China)
  8. Johannes Gutenberg-Univ. Mainz, Mainz (Germany)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1411669
Alternate Identifier(s):
OSTI ID: 1368599
Report Number(s):
LLNL-JRNL-742267
Journal ID: ISSN 0021-8979
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 122; Journal Issue: 1; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Zhang, R. L., Damewood, L., Zeng, Y. J., Xing, H. Z., Fong, C. Y., Yang, L. H., Peng, R. W., and Felser, C. Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect. United States: N. p., 2017. Web. doi:10.1063/1.4989989.
Zhang, R. L., Damewood, L., Zeng, Y. J., Xing, H. Z., Fong, C. Y., Yang, L. H., Peng, R. W., & Felser, C. Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect. United States. doi:10.1063/1.4989989.
Zhang, R. L., Damewood, L., Zeng, Y. J., Xing, H. Z., Fong, C. Y., Yang, L. H., Peng, R. W., and Felser, C. Fri . "Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect". United States. doi:10.1063/1.4989989.
@article{osti_1411669,
title = {Two prospective Li-based half-Heusler alloys for spintronic applications based on structural stability and spin–orbit effect},
author = {Zhang, R. L. and Damewood, L. and Zeng, Y. J. and Xing, H. Z. and Fong, C. Y. and Yang, L. H. and Peng, R. W. and Felser, C.},
abstractNote = {To search for half-metallic materials for spintronic applications, instead of using an expensive trial-and-error experimental scheme, it is more efficient to use first-principles calculations to design materials first, and then grow them. In particular, using a priori information of the structural stability and the effect of the spin–orbit interaction (SOI) enables experimentalists to focus on favorable properties that make growing half-metals easier. We suggest that using acoustic phonon spectra is the best way to address the stability of promising half-metallic materials. Additionally, by carrying out accurate first-principles calculations, we propose two criteria for neglecting the SOI so the half-metallicity persists. As a result, based on the mechanical stability and the negligible SOI, we identified two half-metals, β-LiCrAs and β-LiMnSi, as promising half-Heusler alloys worth growing.},
doi = {10.1063/1.4989989},
journal = {Journal of Applied Physics},
number = 1,
volume = 122,
place = {United States},
year = {Fri Jul 07 00:00:00 EDT 2017},
month = {Fri Jul 07 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • Half-metallic ferromagnetic (HMF) materials show high spin polarization and are therefore interesting to researchers due to their possible applications in spintronic devices. In these materials, while one spin sub band has a finite density of states at the Fermi level, the other sub band has a gap. Because of their high Curie temperature (T{sub C}) and tunable electronic structure, HMF Heusler alloys have a special importance among the HMF materials. Full Heusler alloys with the stoichiometric composition X{sub 2}YZ (where X and Y are the transition metals and Z is a sp element) have the cubic L2{sub 1} structure withmore » four interpenetrating fcc sublattices. When each of these four fcc sublattices is occupied by different atoms (XX′YZ), a quaternary Heusler structure with different structural symmetries (space group F-43m, #216) is obtained. Recently, these equiatomic quaternary Heusler alloys (EQHAs) with 1:1:1:1 stoichiometry have attracted a lot of attention due to their superior magnetic and transport properties. A special class of HMF materials identified recently is known as spin gapless semiconductors (SGS). The difference in this case, compared with HMFs, is that the density of states for one spin band is just zero at the Fermi level, while the other has a gap as in the case of HMFs. Some of the reported SGS materials belong to EQHAs family. This review is dedicated to almost all reported materials belonging to EQHAs family. The electronic structure and hence the physical properties of Heusler alloys strongly depend on the degree of structural order and distribution of the atoms in the crystal lattice. A variety of experimental techniques has been used to probe the structural parameters and degree of order in these alloys. Their magnetic properties have been investigated using the conventional methods, while the spin polarization has been probed by point contact Andreev reflection technique. The experimentally obtained values of saturation magnetization are found to be in agreement with those estimated using the Slater-Pauling rule in most of the cases. Electrical resistivity and Hall measurements are being used to distinguish between SGS and HMF nature in detail. The current spin polarization value, P = 0.70 ± 0.01, for CoFeMnGe is found to be highest among the EQHAs. CoFeMnSi and CoFeCrGa are found to show SGS behavior with high Curie temperatures, thus making them suitable substitutes for diluted magnetic semiconductors. CoRuFeSi is found to have the highest T{sub C} among EQHAs. Theoretical prediction of magnetic properties on the basis of electronic structure calculations has also been reported in a few systems, which are also discussed in this review. Thus, this review presents a consolidated picture of the magnetic and spintronic properties of this important, but relatively new class of Heusler alloys. It is expected that this will stimulate further interest in these alloys, thereby paving the way for the identification of more HMF and SGS materials. As a result of this, it is expected that more efficient spintronic devices using these alloys would emerge in the near future.« less
  • Various full Heusler alloys are interfaced with MgO and the magnetic properties of the Heusler-MgO junctions are studied. Next to MgO, the cubic Heusler system distorts to a tetragonal one, thereby inducing an anisotropy. The half-metallicity and nature of anisotropy (in-plane or perpendicular) in the Heusler-MgO system is governed mostly by the interface Heusler layers. There is a trend that Mn-O bonding near the MgO-Heusler junction results in perpendicular anisotropy. The ability to remain half-metallic and have perpendicular anisotropy makes some of these alloys potential candidates as free-layers in Spin Transfer Torque Random Access Memory (STT-RAM) devices, particularly, Cr{sub 2}MnAs-MgOmore » system with MnAs interface layers and Co{sub 2}MnSi-MgO system with Mn{sub 2} interface layers.« less
  • High-spin-polarization materials are desired for the realization of high-performance spintronic devices. We combine recent experimental and theoretical findings to theoretically design several high-spin-polarization materials in binary D0{sub 3}-type Heusler alloys: gapless (zero-gap) half-metallic ferrimagnets of V{sub 3}Si and V{sub 3}Ge, half-metallic antiferromagnets of Mn{sub 3}Al and Mn{sub 3}Ga, half-metallic ferrimagnets of Mn{sub 3}Si and Mn{sub 3}Ge, and a spin gapless semiconductor of Cr{sub 3}Al. The high spin polarization, zero net magnetic moment, zero energy gap, and slight disorder compared to the ternary and quaternary Heusler alloys make these binary materials promising candidates for spintronic applications. All results are obtained bymore » the electronic structure calculations from first-principles.« less
  • Ab initio calculations are performed to investigate the structural stability, electronic structure, mechanical properties and optical properties of half Heusler alloys (LiBeAs and LiBeSb) for three different phases of zinc blende crystal structure. Among the considered phases, α- phase is found to be the most stable phase for these alloys at normal pressure. A pressure induced structural phase transition from α-phase to β- phase is observed for LiBeAs. The electronic structure reveals that these alloys are semiconductors. The optical properties confirm that these alloys are semiconductor in nature.