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arXiv 1801.04426cond-mat.mes-hall
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用于自旋器件的定制多层量子阱

Tailoring multilayer quantum wells for spin devices

S. Ullah, G. M. Gusev, A. K. Bakarov, F. G. G. Hernandez

摘要:

利用时间分辨Kerr旋转和共振自旋放大技术研究了GaAs/AlGaAs多层量子阱中高迁移率致密二维电子气的自旋动力学。通过波函数工程和多层量子阱中的量子限制来调控电子自旋动力学。在金属-绝缘体转变后掺杂的结构中,我们观察到了自旋相干,并且有一个非常长的退相时间T2* > 13 ns。Dyakonov-Perel自旋弛豫机制以及电子g因子的不均匀性是自旋相干时间的主要限制因素。在金属制度,我们发现,电子-电子碰撞成为占主导地位的电子自旋弛豫与Dyakonov-Perel机制的微观散射。此外,数据分析表明,在我们的结构中,由于自旋弛豫各向异性,Dyakonov-Perel自旋弛豫机制对于自旋取向在平面内是有效的,并且沿着量子阱生长方向被抑制,导致T2* 的增强。我们的研究结果,即,长寿命的自旋相干持续到室温左右,自旋极化衰减时间与无磁场,自旋轨道场,单电子弛豫时间,输运散射时间,和电子-电子库仑散射时间突出的吸引力的n-掺杂的多层系统的自旋器件。

英文摘要:

The electron spin dynamics in multilayer GaAs/AlGaAs quantum wells, containing high-mobility dense two-dimensional electron gases, have been studied using time-resolved Kerr rotation and resonant spin amplification techniques. The electron spin dynamics was regulated through the wave function engineering and quantum confinement in multilayer quantum wells. We observed the spin coherence with a remarkably long dephasing time T2* > 13 ns for the structure doped beyond metal-insulator transition. Dyakonov-Perel spin relaxation mechanism, as well as the inhomogeneity of electron g-factor, was suggested as the major limiting factors for the spin coherence time. In the metallic regime, we found that the electron-electron collisions become dominant over microscopic scattering on the electron spin relaxation with the Dyakonov-Perel mechanism. Furthermore, the data analysis indicated that in our structure, due to the spin relaxation anisotropy, Dyakonov-Perel spin relaxation mechanism is efficient for the spins oriented in-plane and suppressed along the quantum well growth direction resulting in the enhancement of T2*. Our findings, namely, long-lived spin coherence persisting up to about room temperature, spin polarization decay time with and without a magnetic field, the spin-orbit field, single electron relaxation time, transport scattering time, and the electron-electron Coulomb scattering time highlight the attractiveness of n-doped multilayer systems for spin devices.

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