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arXiv 2401.01658cond-mat.mes-hall
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应用于5$d$金属的本征自旋霍尔效应的从头算输运理论

Ab-initio transport theory for the intrinsic spin Hall effect applied to 5$d$ metals

Akash Bajaj, Reena Gupta, Ilya V. Tokatly, Stefano Sanvito, Andrea Droghetti

AI总结:

本文提出结合密度泛函理论与非平衡格林函数的DFT+NEGF方法从头算研究自旋霍尔效应,计算了5d金属的弹道自旋霍尔电导率,并预测了晶胞内电流诱导的自旋偶极矩。

摘要:

我们描述了如何通过将密度泛函理论与用于量子输运的非平衡格林函数技术相结合,形成所谓的DFT+NEGF方法,从而从头算研究自旋霍尔效应(SHE)。在奠定我们的理论基础时,特别讨论了如何计算电荷和自旋键合电流,随后对理想纯净系统进行了DFT+NEGF计算。在这些系统中,输运是弹道式的,并且满足线性响应极限。当我们在连接到两个电极的中心区域施加偏压,使电子被均匀电场加速时,SHE便会出现。结果表明,我们获得了有限的自旋霍尔电流,并通过对系统尺寸进行标度分析,估算了弹道自旋霍尔电导率(SHC)。我们考虑了具有fcc和bcc晶体结构的5d金属,发现SHC对d带填充表现出粗略的定性依赖关系,并结合现有文献对这些结果进行了评述。最后,在同一DFT+NEGF方法框架内,我们还预测了材料晶胞内部会出现电流诱导的自旋偶极矩,并估算了其大小。

英文摘要:

We describe how the spin Hall effect (SHE) can be studied from ab-initio by combining density functional theory with the non-equilibrium Green's functions technique for quantum transport into the so-called DFT+NEGF method. After laying down our theoretical approach in particular discussing how to compute charge and spin bond currents, DFT+NEGF calculations are carried out for ideal clean systems. In these the transport is ballistic and the linear response limit is met. The SHE emerges in a central region attached to two leads when we apply a bias voltage so that electrons are accelerated by a uniform electric field. As a result, we obtain a finite spin-Hall current and, by performing a scaling analysis with respect to the system size, we estimate the ballistic spin Hall conductivity (SHC). We consider 5d metals with fcc and bcc crystal structures, finding that the SHC exhibits a rough qualitative dependence on the d-band filling, and comment on these results in relation to existing literature. Finally, within the same DFT+NEGF approach, we also predict the appearance of a current-induced spin dipole moment inside the materials' unit cell and estimate its magnitude.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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