方钴矿材料中增强和符号可逆的自旋霍尔与自旋能斯特电导率的从头设计

中文摘要 AI 辅助

寻找能够稳定产生自旋电流的新型材料仍然是一个活跃的研究领域。在此，我们研究了Co基和Rh基方钴矿中的本征自旋霍尔和自旋能斯特效应，并探索了通过重金属替代和位点选择性掺杂来增强这些效应。利用第一性原理计算和基于Wannier的紧束缚模型，我们分析了原始MX$_3$（其中M = Co, Rh，X = As, Sb）以及化学改性系统的自旋Berry曲率和自旋输运响应。尽管动量分辨的自旋Berry曲率相当可观，但由于布里渊区内的显著抵消，原始化合物表现出相对较小的净自旋霍尔响应。在8$c$ Wyckoff M位点进行等电子Ir和Bi替代在E$_F$附近产生的增强很小，而非等电子Pt替代则产生相对更好的响应。最有趣的是，在RhAs$_3$的间隙$2a$ Wyckoff位点掺入Pt，与8$c$位点的Pt替代相比，E$_F$附近的自旋霍尔电导率几乎翻倍，达到约$400~(\hbar/e)(\Omega,\mathrm{cm})^{-1}$。在300 K下，同一间隙填充系统在E$_F$处表现出约$1.46~(\hbar/e),\mathrm{A,m^{-1}K^{-1}}$的自旋能斯特电导率，比$M$位点Pt替代大近一个数量级。增强的响应源于Pt $5d$态、强自旋轨道耦合以及产生显著自旋Berry曲率热点的避免交叉。这些结果表明，位点选择性化学工程可以有效克服动量空间抵消，从而在方钴矿中实现增强的自旋霍尔和自旋能斯特响应。我们的结果为这类材料中稳定自旋电流的产生提供了一条可能的途径。

英文摘要

The search for novel materials capable of robust spin-current generation remains an active area of research. Here, we investigate the intrinsic spin Hall and spin Nernst effects in Co- and Rh-based skutterudites and explore their enhancement through heavy-metal substitution and site-selective doping. Using first-principles calculations and Wannier-based tight-binding models, we analyze the spin Berry curvature and spin-transport responses of pristine MX$_3$, where M = Co, Rh and X = As, Sb, as well as chemically modified systems. Despite sizable momentum-resolved spin Berry curvature, the pristine compounds exhibit relatively small net spin Hall responses due to substantial cancellation across the Brillouin zone. Isoelectronic Ir and Bi substitution at 8$c$ Wycoff M site produces little enhancement near the E$_F$, whereas non-isoelectronic Pt substitution yields a relatively better response. Most interestingly, the incorporation of Pt at the interstitial $2a$ Wycoff site of RhAs$_3$ nearly doubles the spin Hall conductivity to $\sim400~(\hbar/e)(Ω,\mathrm{cm})^{-1}$ near the E$_F$ when compared to Pt substitution at 8$c$ position. At 300 K, the same interstitially filled system exhibits a spin Nernst conductivity of $\sim1.46~(\hbar/e),\mathrm{A,m^{-1}K^{-1}}$ at the E$_F$, nearly an order of magnitude larger than that of $M$-site Pt substitution. The enhanced responses arise from Pt $5d$ states, strong spin-orbit coupling, and avoided crossings that generate pronounced spin-Berry-curvature hot spots. These results demonstrate that site-selective chemical engineering can effectively overcome momentum-space cancellation resulting in enhanced spin Hall and spin Nernst responses in skutterudites. Our results provide a possible route towards robust spin-current generation in this class of materials.

发表机构

• M. V. College（M.V.学院）
• Institute for Solid State Physics, The University of Tokyo（东京大学固体物理研究所）
• Birla Institute of Technology and Science（比尔拉理工学院）

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