Phase stability and the effect of lattice distortions on electronic properties and half-metallic ferromagnetism of Co2FeAl Heusler alloy: An ab initio study
Density functional theory calculations within the generalized gradient approximation are employed to study the ground state of Co2FeAl. Various magnetic configurations are considered to find out its most stable phase. The ferromagnetic ground state of the Co2FeAl is energetically observed with an optimized lattice constant of 5.70 Å. Thereafter, the system was subjected under uniform and non-uniform strains to see their effects on spin polarization (P) and half-metallicity. The effect of spin orbit coupling is considered in the present study. Half-metallicity (and 100 % P) is only retained under uniform strains started from 0 to +4%, and dropped rapidly from 90% to 16% for the negative strains started from -1% to -6%. We find that the present system is much sensitive under tetragonal distortions as half-metallicity (and 100% P) is preserved only for the cubic case. The main reason for the loss of half-metallicity is due to the shift of the bands with respect to the Fermi level. We also discuss the influence of these results on spintronics devices.
Theory of Huge Thermoelectric Effect Based on Magnon Drag Mechanism: Application to Thin-Film Heusler Alloy
为了理解在薄膜Heusler合金Fe $_2$ V $_{0.8}$ W $_{0.2}$ Al中观察到的出乎意料的高热电性能，我们研究了由钨基杂质带产生的磁振子拖曳效应，作为这种增强的可能来源，类似于在FeSb $_2$中观察到的声子拖曳。假设薄膜Heusler合金具有与杂质带结合的导带，由钨替代产生，我们基于自洽t矩阵近似推导了电导率$L_{11}$，基于线性响应理论推导了磁振子拖曳引起的热电电导率$L_{12}$，并估算了电阻率、Seebeck系数和功率因数随温度的变化.最后，我们将理论结果与薄膜Heusler合金的实验结果进行了比较，结果表明，异常热电性能的起源很可能是由于与钨基杂质带相关的磁振子阻力。
Direct measurements of the magnetocaloric effect in ribbon samples of Heusler alloys Ni - Mn - M (M = In, Sn)
直接测量的磁热效应在快速淬火薄带的Mn 50 Ni 40 In 10和Ni 50 Mn 37 Sn 13 Heusler合金，在磁制冷技术的潜在应用，样品进行。测量是通过一种精确的方法进行的，该方法是基于测量样品在受到调制磁场的同时温度的振荡幅度。在所研究的成分中，发现了与磁性（顺磁体-铁磁体-反铁磁体）和结构（奥氏体-马氏体）相变相关的正磁热效应和逆磁热效应，在铁磁相变附近还观察到了小值的逆磁热效应。
Electron Correlations and the Minority-Spin Band Gap in Half-Metallic Heusler Alloys
电子-电子关联通过在费米能级之上引入非准粒子态来影响半金属铁磁体的带隙。与自旋轨道耦合不同，少数自旋通道中存在较大的非对称非准粒子谱权重，导致了特殊的有限温度自旋去极化效应。利用最近发展的第一性原理动力学平均场论，我们研究了半金属铁磁Heusler化合物FeMnSb的这些效应。讨论了FeMnSb中局部库仑相互作用$U$强度和温度对退极化效应的影响。我们提出了Ni $_{1-x}$ Fe $_{x}$ MnSb合金作为一种有前景的材料，用于自旋阀结构和半金属材料中的非准粒子态的实验研究。
Local magnetic structure in fully and partially ordered V$_2$$X$Al Heusler alloys ($X$=Cr, Mn, Fe, Co, Ni)
University of Science and Technology Beijing（北京科技大学）；State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing（北京科技大学先进金属与材料国家重点实验室）
