Interplay of growth mode and thermally induced spin accumulation in epitaxial Al/Co2TiSi/Al and Al/Co2TiGe/Al contacts
Interplay of growth mode and thermally induced spin accumulation in epitaxial Al/Co2TiSi/Al and Al/Co2TiGe/Al contacts
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DOI：
10.1103/physrevb.89.184422
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发表时间：
2014-02
影响因子：
3.7
通讯作者：
B. Geisler;P. Kratzer;V. Popescu
中科院分区：
文献类型：
--
作者：
B. Geisler;P. Kratzer;V. Popescu
通过热力学平衡和电子传输的{\em ab initio}计算，研究了由插入铝引线之间的半金属霍斯勒合金制成的热驱动自旋注入器的可行性。我们关注两个主要问题并发现：(i) Al 和 Co$_2$Ti$Z$ ($Z=$ Si 或 Ge) 型紧密晶格匹配的 Heusler 合金之间的界面在各种生长条件下都是稳定的； (ii) 这种异质结中的常规塞贝克系数和自旋相关塞贝克系数表现出对间隔基和 Al/Heusler 界面的原子组成的强烈依赖性。后一个量给出了自旋累积的度量，并且在 $+8$~$\mu$V/K 和 $-3$~$\mu$V/K 之间变化，接近 $300$~K，具体取决于 Ti-Ge 或 Co-Co 平面是否在三层中的 Al 和 Co$_2$TiGe 之间进行接触。我们的结果表明，原则上可以通过对样品进行有针对性的生长控制来定制自旋热量效应。
The feasibility of thermally driven spin injectors built from half-metallic Heusler alloys inserted between aluminum leads was investigated by means of {\em ab initio} calculations of the thermodynamic equilibrium and electronic transport. We have focused on two main issues and found that: (i) the interface between Al and the closely lattice-matched Heusler alloys of type Co$_2$Ti$Z$ ($Z=$ Si or Ge) is stable under various growth conditions; and (ii) the conventional and spin-dependent Seebeck coefficients in such heterojunctions exhibit a strong dependence on both the spacer and the atomic composition of the Al/Heusler interface. The latter quantity gives a measure of the spin accumulation and varies between $+8$~$\mu$V/K and $-3$~$\mu$V/K near $300$~K, depending on whether a Ti-Ge or a Co-Co plane makes the contact between Al and Co$_2$TiGe in the trilayer. Our results show that it is in principle possible to tailor the spin-caloric effects by a targeted growth control of the samples.