论文标题
各向异性旋转大厅和旋转nernst效果
Anisotropic spin Hall and spin Nernst effects in bismuth semimetal
论文作者
论文摘要
Bismuth是一种具有巨大的自旋轨道耦合的原型半学，它一直是在固态物理学中发现精液现象的主要原始材料。近年来，当前在二抗性的旋转运输也引起了很大的关注。在本文中，我们基于相对论带结构计算，理论上研究了Bismuth中旋转厅效应（SHA）和旋转Nernst效应（SNE）。首先，我们发现旋转厅电导率（SHC）和旋转Nernst电导率（SNC）有三个独立的张量元素，即$ z_ {yx}^z $，$ z_ {xz}^y $，$ z__ {z__ {zy}^x $。我们将所有元素计算为费米能量的函数。其次，我们发现所有SHC张量元素都很大，为$ \ sim $ 1000（$ \ hbar $/e）（s/cm），与铂金的元素相当。此外，由于其低电导率，相应的旋转大厅角度巨大，$ \ sim $ 20％。第三，所有计算出的SNC张量元件也很明显，与黄金的[$ \ sim $ 0.13（$ \ hbar $/e）（a/m-k）]相当，尽管它们比白金和$β$ -TA小几倍。最后，与pt and au相反，其中$ z_ {yx}^z = z_ {xz}^y = z__ = z_ {zy}^x $，bismuth中的she and sne非常强烈，即，即，$ z__ {yx}^z $，$ z_ {yx}^z $，$ z______ {xz} y $ z_ $}^y $}^y $}^y $}因此，由于使用多晶样品，由于不同的电导率元素的反面和SNE而导致的霍尔电压可能会相互取消，因此导致小旋转厅角度，这可以解释为什么测量的旋转大厅的角度范围为近0至25％。我们希望这些有趣的发现能够使用高度定向的单晶标本在Bismuth上进行进一步的自旋当前实验。
Bismuth is an archetypal semimetal with gigantic spin-orbit coupling and it has been a major source material for the discovery of seminal phenomena in solid state physics for more than a century. In recent years, spin current transports in bismuth have also attracted considerable attention. In this paper, we theoretically study both spin Hall effect (SHE) and spin Nernst effect (SNE) in bismuth, based on relativistic band structure calculations. First, we find that there are three independent tensor elements of spin Hall conductivity (SHC) and spin Nernst conductivity (SNC), namely, $Z_{yx}^z$, $Z_{xz}^y$, and $Z_{zy}^x$. We calculate all the elements as a function of the Fermi energy. Second, we find that all SHC tensor elements are large, being $\sim$1000 ($\hbar$/e)(S/cm) and comparable to that of platinum. Furthermore, because of its low electrical conductivity, the corresponding spin Hall angles are gigantic, being $\sim$20%. Third, all the calculated SNC tensor elements are also pronounced, being comparable to that [$\sim$0.13 ($\hbar$/e)(A/m-K)] of gold, although they are several times smaller than platinum and $β$-Ta. Finally, in contrast to Pt and Au where $Z_{yx}^z = Z_{xz}^y = Z_{zy}^x$, the SHE and SNE in bismuth are strongly anisotropic, i.e., $Z_{yx}^z$, $Z_{xz}^y$ and $Z_{zy}^x$ differ significantly. Consequently, the Hall voltages due to the inverse SHE and SNE from the different conductivity elements could cancel each other and thus result in a small spin Hall angle if polycrystalline samples are used, which may explain why the measured spin Hall angles ranging from nearly 0 to 25% have been reported. We hope that these interesting findings would stimulate further spin current experiments on bismuth using highly oriented single crystal specimens.
