Exact SU(2) symmetry and persistent spin helix in a spin-orbit coupled system
Exact SU(2) symmetry and persistent spin helix in a spin-orbit coupled system
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DOI：
10.1103/physrevlett.97.236601
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发表时间：
2006-12-08
影响因子：
8.6
通讯作者：
Zhang, Shou-Cheng
中科院分区：
文献类型：
--
作者：
Bernevig, B. Andrei;Orenstein, J.;Zhang, Shou-Cheng
自旋-轨道耦合系统通常会破坏自旋旋转对称性。然而，对于具有相等Rashba和Dresselhauss耦合常数的模型，以及[110] Dresselhauss模型，发现了一种新的SU（2）自旋旋转对称性。这种对称性对自旋无关的无序和相互作用是鲁棒的，并且是由波矢取决于耦合强度的算子产生的。它使自旋寿命在这个波矢上无限大，从而产生一个持久的自旋螺旋。我们得到的自旋波动动力学，远离对称点，并建议实验观察持久的自旋螺旋。
Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constants, and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions and is generated by operators whose wave vector depends on the coupling strength. It renders the spin lifetime infinite at this wave vector, giving rise to a persistent spin helix. We obtain the spin fluctuation dynamics at, and away from, the symmetry point and suggest experiments to observe the persistent spin helix.