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arXiv 1012.1074cond-mat.mes-hallcond-mat.mtrl-sci
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晶格基双量子点中受限声子诱导的电子自旋弛豫的电操纵

Electric manipulation of electron spin relaxation induced by confined phonons in nanowire-based double quantum dots

M. Wang, Y. Yin, M. W. Wu

摘要:

从理论上研究了单电子空穴型半导体双量子点中受束缚声子诱导的电子自旋弛豫,发现在这种体系中,电子自旋弛豫速率可以被外加电场有效地调控.由于电场、磁场和自旋轨道耦合的共同作用,在最低的两个激发态之间存在一个反交叉。反交叉点周围的电场可以有效地调节电子态的能量和自旋。多个尖锐的峰存在于电场的依赖性的自旋弛豫率由受限声子,这可以归因于大的态密度的受限声子在范霍夫奇点。这一特性表明,基于双量子点的可调谐自旋开关,这是更灵敏和灵活的比基于量子阱的双量子点的电可调谐开关。计算了自旋弛豫速率在反交叉点处的温度依赖关系,观察到一个光滑的峰,表明密度矩阵的非对角元素对自旋弛豫的重要贡献.

英文摘要:

We investigate theoretically the electron spin relaxation in single-electron nanowire-based semiconductor double quantum dots induced by confined phonons and find that the electron spin relaxation rate can be efficiently manipulated by external electric fields in such system. An anti-crossing, due to the coaction of the electric field, the magnetic field and the spin-orbit coupling, exists between the lowest two excited states. Both energies and spins of the electron states can be efficiently tuned by the electric field around the anti-crossing point. Multiple sharp peaks exist in the electric-field dependence of the spin relaxation rate induced by the confined phonons, which can be ascribed to the large density of states of the confined phonons at the van Hove singularities. This feature suggests that the nanowire-based double quantum dots can be used as electric tunable on-and-off spin switches, which are more sensitive and flexible than the ones based on quantum-well based double quantum dots. The temperature dependence of the spin relaxation rate at the anti-crossing point are calculated and a smooth peak, indicating the importance of the contribution of the off-diagonal elements of the density matrix to the spin relaxation, is observed.

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