电子关联下Rashba-Dresselhaus平面带中的自旋霍尔效应
Spin Hall effect in Rashba-Dresselhaus planar strips in the presence of electron correlations
摘要：
本文研究了零温、四分之一填充的平面带上同时具有Rashba和Dresselhaus自旋轨道（SO）耦合和Hubbard电子-电子相互作用的模型。在没有哈伯德排斥和平衡，在线性响应理论，自旋霍尔电导率的Rashba（α）和Dresselhaus（β）强度的比例的函数的非单调行为被发现足够大的SO强度。这种行为通过在区间[0，1]中的β/α中间值处的峰值或尖点来表示，具体取决于条带宽度。自旋霍尔电导率的这种行为与纵向自旋电导率的行为相关。这项研究，然后扩展到平衡制度，所产生的施加有限的电压偏置之间的两端的开放带。这个系统，在一个耦合U的Hubbard项的存在下，处理与密度矩阵重整化群技术和Landauer-Buttiker形式。结果发现，自旋霍尔效应的相关属性，如横向自旋电流和自旋积累，呈现出类似的非单调行为的自旋电导率。更重要的是，我们还发现，这些性质的增强，由排斥哈伯德相互作用，直到一个中等值的U。
英文摘要：
A model with both Rashba and Dresselhaus spin orbit (SO) couplings and Hubbard electron-electron interaction is studied on planar strips at quarter filling at zero temperature in the clean limit. In the absence of Hubbard repulsion and at equilibrium, within linear response theory, a nonmonotonic behavior of the spin Hall conductivity as a function of the ratio of the Rashba (alpha) and Dresselhaus (beta) strengths was found for large enough SO strengths. This behavior is signalled by a peak or a cusp, depending on the strip width, at intermediate values of beta/alpha in the interval [0,1]. This behavior of the spin Hall conductivity was correlated with the one for the longitudinal spin conductivity. This study was then extended to the out-of-equilibrium regime that arises by imposing a finite voltage bias between the two ends of an open strip. This system, in the presence of a Hubbard term with coupling U, was treated with the density matrix renormalization group technique and with the Landauer-Buttiker formalism. It was found that relevant properties to the spin Hall effect, such as the transversal spin current and the spin accumulation, present a similar nonmonotonic behavior as the one found for the spin conductivities. More importantly, it was also found that these properties are enhanced by the repulsive Hubbard interaction up to a moderate value of U.
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