arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0803.3579cond-mat.mes-hallcond-mat.str-el
收藏

单势垒异质结准二维系统第二子带自旋动力学的时间分辨Kerr旋转研究

Spin Dynamics in the Second Subband of a Quasi Two Dimensional System Studied in a Single Barrier Heterostructure by Time Resolved Kerr Rotation

F. Zhang, H. Z. Zheng, Y. Ji, J. Liu, G. R. Li

备注：
9pages, 3 figures
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

通过偏置一个500 nm厚的GaAs层作为吸收层的单势垒异质结，研究了AlAs势垒附近的第一和第二子带的自旋动力学。我们发现，当同时扫描探测和泵浦光的光子能量时，只要探测光子脱离第一子带并探测第二子带，克尔旋转（KR）就会发生符号反转。这个新的特征，虽然源于交换相互作用，但已被用来明确区分不同条件下第一和第二子带的不同自旋动力学（$T_2^{1*}$和$T_2^{2*}$），通过它们的KR符号（$1^{st}$为负，$2^{nd}$为正）。在零磁场中，通过向短波长扫描波长，$T_2^{1*}$根据D 'yakonov-Perel'（DP）自旋退相干机制减小。在803 nm处，$T_2^{2*}$（450 ps）变得比$T_2^{1*}$（50 ps）长十倍。然而，803 nm处的$T_2^{2*}$值与815 nm处的$T_2^{1*}$值大致相同。在-0.3V偏压下波长为811 nm（-0.6V偏压下波长为807 nm），自旋相干时间（$T_2^{1*}$和$T_2^{2*}$）和有效$g^*$因子（$|g^*(E1)|$和$|g^*(E2)|$）均出现突变，这是由于两个自旋相反的带之间的“共振”自旋交换耦合引起的.

英文摘要：

By biasing a single barrier heterostructure with a 500nm-thick GaAs layer as the absorption layer, the spin dynamics for both of the first and second subband near the AlAs barrier are examined. We find that when simultaneously scanning the photon energy of both the probe and pump beams, a sign reversal of the Kerr rotation (KR) takes place as long as the probe photons break away the first subband and probe the second subband. This novel feature, while stemming from the exchange interaction, has been used to unambiguously distinguish the different spin dynamics ($T_2^{1*}$ and $T_2^{2*}$) for the first and second subbands under the different conditions by their KR signs (negative for $1^{st}$ and positive for $2^{nd}$). In the zero magnetic field, by scanning the wavelength towards the short wavelength, $T_2^{1*}$ decreases in accordance with the D'yakonov-Perel' (DP) spin decoherence mechanism. At 803nm, $T_2^{2*}$(450ps) becomes ten times longer than $T_2^{1*}$(50ps). However, the value of $T_2^{2*}$ at 803nm is roughly the same as the value of $T_2^{1*}$ at 815nm. A new feature has been disclosed at the wavelength of 811nm under the bias of -0.3V (807nm under the bias of -0.6V) that the spin coherence times ($T_2^{1*}$ and $T_2^{2*}$) and the effective $g^*$ factors ($|g^*(E1)|$ and $|g^*(E2)|$) all display a sudden change, due to the "resonant" spin exchange coupling between two spin opposite bands.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑