Dóra Balázs, Simon Ferenc
BME-MTA Exotic Quantum Phases Research Group, Budapest University of Technology and Economics, PoBox 91, H-1521 Budapest, Hungary.
Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendulet Spintronics Research Group (PROSPIN), PoBox 91, H-1521 Budapest, Hungary.
Sci Rep. 2015 Oct 6;5:14844. doi: 10.1038/srep14844.
The dynamic spin susceptibility (DSS) has a ubiquitous Lorentzian form around the Zeeman energy in conventional materials with weak spin orbit coupling, whose spectral width characterizes the spin relaxation rate. We show that DSS has an unusual non-Lorentzian form in topological insulators, which are characterized by strong SOC, and the anisotropy of the DSS reveals the orientation of the underlying spin texture of topological states. At zero temperature, the high frequency part of DSS is universal and increases in certain directions as ω(d-1) with d = 2 and 3 for surface states and Weyl semimetals, respectively, while for helical edge states, the interactions renormalize the exponent as d = 2K - 1 with K the Luttinger-liquid parameter. As a result, spin relaxation rate cannot be deduced from the DSS in contrast to the case of usual metals, which follows from the strongly entangled spin and charge degrees of freedom in these systems.
在具有弱自旋轨道耦合的传统材料中，动态自旋磁化率（DSS）在塞曼能量附近具有普遍存在的洛伦兹形式，其谱宽表征自旋弛豫率。我们表明，在以强自旋轨道耦合为特征的拓扑绝缘体中，DSS具有不寻常的非洛伦兹形式，并且DSS的各向异性揭示了拓扑态潜在自旋纹理的取向。在零温度下，DSS的高频部分是通用的，对于表面态和外尔半金属，分别在特定方向上随ω(d - 1)增加，其中d = 2和3，而对于螺旋边缘态，相互作用将指数重整化为d = 2K - 1，K为卢廷格液体参数。因此，与普通金属的情况不同，不能从DSS推断出自旋弛豫率，这是由这些系统中自旋和电荷自由度的强纠缠导致的。
