Dynamics of a localized spin excitation close to the spin-helix regime
Dynamics of a localized spin excitation close to the spin-helix regime
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接近自旋螺旋状态的局部自旋激发的动力学
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
W. Wegscheider
中科院分区：
文献类型：
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作者：
G. Salis;M. Walser;P. Altmann;C. Reichl;W. Wegscheider
从理论上研究了（001）受限二维电子气体在Rashba和Dresselhaus两种相似强度的自旋轨道相互作用下的局域自旋激发的时间演化，并与实验数据进行了比较。具体来说，研究了非平衡Rashba项和Dresselhaus项以及有限立方Dresselhaus自旋-轨道相互作用下初始自旋极化有限空间扩展的结果。我们发现初始的面外自旋极化演变为螺旋自旋模式，其波数逐渐接近持续自旋螺旋模式的值$q_0$。除了自旋极化的指数衰减与自旋轨道不平衡和三次Dresselhaus项成比例外，自旋激发的有限宽度w减少了自旋极化，其因子在较长时间内接近exp(-q_0^2 w^2/2)$。
The time evolution of a local spin excitation in a (001)-confined two-dimensional electron gas subjected to Rashba and Dresselhaus spin-orbit interactions of similar strength is investigated theoretically and compared with experimental data. Specifically, the consequences of the finite spatial extension of the initial spin polarization is studied for non-balanced Rashba and Dresselhaus terms and for finite cubic Dresselhaus spin-orbit interaction. We show that the initial out-of-plane spin polarization evolves into a helical spin pattern with a wave number that gradually approaches the value $q_0$ of the persistent spin helix mode. In addition to an exponential decay of the spin polarization that is proportional to both the spin-orbit imbalance and the cubic Dresselhaus term, the finite width $w$ of the spin excitation reduces the spin polarization by a factor that approaches $exp(-q_0^2 w^2/2)$ at longer times.