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arXiv 2101.01906cond-mat.quant-gas
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Rashba和Dresselhaus自旋轨道耦合下自旋霍尔效应的解析解模型

Analytically solvable model to the spin Hall effect with Rashba and Dresselhaus spin-orbit couplings

Rui Zhang, Yuan-Chuan Biao, Wen-Long You, Xiao-Guang Wang, Yu-Yu Zhang

摘要:

当二维电子在垂直磁场中存在Rashba和Dresslhaus自旋轨道耦合时,发现它们与量子光学中的各向异性量子Rabi模型有着惊人的相似之处,我们采用广义Rashba耦合近似,通过保留Laudau态的最近混合项,得到了一个可解的哈密顿量,并将其重新表述为与仅存在Rashba耦合的哈密顿量类似的形式.每一个朗道态都是一个新的位移Fock态,取代了原来的谐振子Fock态,得到了封闭形式的本征态。在很宽的耦合强度范围内,即使对于强塞曼分裂,分析能量也与数值能量一致。在有电场存在的情况下,自旋电导和电荷电导的解析计算结果与数值计算结果符合得很好。随着Dresselhaus耦合分量的增加,我们发现自旋霍尔电导在磁场的倒数较大时呈现出明显的共振峰。同时,电荷电导在谐振磁场处呈现出一系列的平台和跳跃。我们的方法提供了一个易于实现的分析处理二维电子气系统的两种类型的自旋轨道耦合。

英文摘要:

When the Rashba and Dresslhaus spin-orbit coupling are both presented for a two-dimensional electron in a perpendicular magnetic field, a striking resemblance to anisotropic quantum Rabi model in quantum optics is found. We perform a generalized Rashba coupling approximation to obtain a solvable Hamiltonian by keeping the nearest-mixing terms of Laudau states, which is reformulated in the similar form to that with only Rashba coupling. Each Landau state becomes a new displaced-Fock state with a displacement shift instead of the original Harmonic oscillator Fock state, yielding eigenstates in closed form. Analytical energies are consistent with numerical ones in a wide range of coupling strength even for a strong Zeeman splitting. In the presence of an electric field, the spin conductance and the charge conductance obtained analytically are in good agreements with the numerical results. As the component of the Dresselhaus coupling increases, we find that the spin Hall conductance exhibits a pronounced resonant peak at a larger value of the inverse of the magnetic field. Meanwhile, the charge conductance exhibits a series of plateaus as well as a jump at the resonant magnetic field. Our method provides an easy-to-implement analytical treatment to two-dimensional electron gas systems with both types of spin-orbit couplings.

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