Ferri-chiral compounds with potentially switchable Dresselhaus spin splitting
Ferri-chiral compounds with potentially switchable Dresselhaus spin splitting
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具有潜在可切换 Dresselhaus 自旋分裂的 Ferri 手性化合物
DOI：
10.1103/physrevb.102.235127
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发表时间：
2020-07
影响因子：
3.7
通讯作者：
Zunger Alex
中科院分区：
文献类型：
--
作者：
Huang Pu;Xia Zhiguo;Gao Xiaoqing;Rondinelli James M.;Zhang Xiuwen;Zhang Han;Poeppelmeier Kenneth R.;Zunger Alex
在没有反转对称性的材料中，相对论自旋-轨道相互作用可以引起能带的自旋分裂。虽然极空间群对称性允许动量空间中具有螺旋自旋织构的Rashba(R-1)自旋分裂，但通过外加电场切换铁电极化可以逆转这种分裂，而普通的Dresselhaus效应(D-1A)只在原子只占据非极性晶位的非极性非中心对称晶类的材料中起作用。因此，D-1A引起的自旋-动量锁定不是电场可切换的。另一种类型的Dresselhaus对称，称为D-1B，表现出类似于D-1A的晶级限制(所有偶极子加起来为零)，但与D-1A不同的是，至少占据了一个极位。我们发现，这一行为存在于一类手性铁晶体中，原则上，手性变化可以逆转这一行为。以碱金属硫属化合物为研究对象，我们在非全变质铁-手性结构中发现了NaCu5S3，它表现出不同的CuS3手性单元的铜位移量。然后我们合成了NaCu5S3(空间群P6322)，并用功率X射线衍射法确定了它的铁手性结构。我们的电子结构计算表明，它表现出D-1B自旋分裂以及铁-手性相变，揭示了自旋分裂与手性相互依赖。我们的电子结构计算表明，几个百分点的双向拉伸应变可以降低(或几乎猝灭)分离单畴铁手性P6322态的开关势垒。我们讨论了什么类型的外部刺激可以改变手性从而逆转(非螺旋的)Dresselhaus D-1B自旋织构，为传统的(螺旋的)Rashba自旋织构的逆转提供了一种选择。
Spin splitting of energy bands can be induced by relativistic spin-orbit interactions in materials without inversion symmetry. Whereas polar space group symmetries permit Rashba (R-1) spin splitting with helical spin textures in momentum space, which could be reversed upon switching a ferroelectric polarization via applied electric fields, the ordinary Dresselhaus effect (D-1A) is ac-tive only in materials exhibiting nonpolar noncentrosymmetric crystal classes with atoms occupy-ing exclusively non-polar lattice sites. Consequently, the spin-momentum locking induced by D-1A is not electric field-switchable. An alternative type of Dresselhaus symmetry, referred to as D-1B, exhibits crystal class constraints similar to D-1A (all dipoles add up to zero), but unlike D-1A, at least one polar site is occupied. We find that this behavior exists in a class of ferri-chiral crys-tals, which in principle could be reversed upon a change in chirality. Focusing on alkali metal chalcogenides, we identify NaCu5S3 in the nonentiamorphic ferri-chiral structure, which exhibits CuS3 chiral units differing in the magnitude of their Cu displacements. We then synthesize NaCu5S3 (space group P6322) and confirm its ferri-chiral structure with power x-ray diffraction. Our electronic structure calculations demonstrate it exhibits D-1B spin splitting as well as a ferri-chiral phase transition, revealing spin splitting interdependent on chirality. Our electronic struc-ture calculations show that a few percent biaxial tensile strain can reduce (or nearly quench) the switching barrier separating the monodomain ferri-chiral P6322 states. We discuss what type of external stimuli might switch the chirality so as to reverse the (non-helical) Dresselhaus D-1B spin texture, offering an alternative to the traditional reversal of the (helical) Rashba spin texture.
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