135型Kagome金属家族中显著的本征轨道霍尔效应及环流相的轨道响应
Prominent Intrinsic Orbital Hall Effect in the 135 Kagome Metal Family and Orbital Responses in the Loop-Current Phase
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中文总结 AI 辅助
该研究针对135型Kagome金属，揭示不同化合物的轨道霍尔效应符号差异，阐明轨道分量及杂化的调控作用，还明确CsV$_3$Sb$_5环流相的局域轨道角动量与轨道电导率张量对称分量特性，为相关研究奠定基础。
中文摘要 AI 辅助
对电子轨道自由度（包括轨道电流与轨道角动量的产生和调控）的研究已成为一个蓬勃发展的领域。本研究聚焦轨道霍尔效应（OHE，轨道电流产生的关键机制之一），针对过渡金属Kagome晶格金属展开研究。我们提出，CsTi$_3$Bi$_5$模型具有大的正OHE，而CsV$_3$Sb$_5$和CsCr$_3$Sb$_5$模型则具有负OHE。轨道分量分解显示，$\boldsymbol{|l^z_d|=2}$的d轨道通道贡献正效应，而$\boldsymbol{|l^z|=1}$的d轨道和p轨道通道可贡献负效应。对照计算表明，在实际填充附近，轨道分量的符号倾向保持稳定，而强p-d杂化会调控定量平衡及总OHE的符号。因此，OHE的化合物与填充依赖性既反映各轨道分量的符号倾向，也反映由杂化调控的分量间平衡。此外，我们研究了CsV$_3$Sb$_5的环流相，表明其会诱导有限的局域原子轨道角动量；还发现与环流相关的对称性降低可使轨道电导率张量产生有限的对称分量。本研究为探索强关联Kagome金属中的轨道电流及局域轨道角动量响应提供了基础。
英文摘要
The study of electronic orbital degrees of freedom, including the generation and control of orbital currents and orbital angular momentum, has emerged as a vibrant research field. Here, we study the orbital Hall effect (OHE), one of the key mechanisms for orbital current generation, in transition-metal kagome-lattice metals. We propose a large positive OHE in CsTi$_3$Bi$_5$ and negative OHEs in CsV$_3$Sb$_5$ and CsCr$_3$Sb$_5$ models. Orbital-sector decomposition shows that the $\vert l^z_d \vert=2$ $d$-orbital channel gives a positive contribution, whereas the $\vert l^z \vert=1$ $d$- and $p$-orbital channels can give negative contributions. Control calculations suggest a persistent orbital-sector sign tendency near the actual filling, while strong $p$-$d$ hybridization modulates the quantitative balance and total OHE sign. Thus, the compound and filling dependence of the OHE reflects both the sign tendency of each orbital sector and the hybridization-controlled balance among them. Furthermore, we investigate the loop-current phase of CsV$_3$Sb$_5$ and show that it induces finite local atomic orbital angular momentum. We also show that loop-current-related symmetry lowering allows finite symmetric components of the orbital conductivity tensor. This study provides a basis for exploring orbital currents and local orbital-angular-momentum responses in strongly correlated kagome metals.
