Origins of overshoots in the exciton spin dynamics in semiconductors
Origins of overshoots in the exciton spin dynamics in semiconductors
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DOI：
10.1103/physrevb.99.165308
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发表时间：
2019-02
影响因子：
3.7
通讯作者：
F. Ungar;M. Cygorek;V. M. Axt
中科院分区：
文献类型：
--
作者：
F. Ungar;M. Cygorek;V. M. Axt
我们研究了共振光激发后激子自旋动力学中过冲的起源。作为一个材料系统，我们专注于稀磁半导体量子威尔斯，因为它们提供了一个强大的自旋翻转散射的载流子。我们的研究表明，在没有任何记忆的理论中，即使在单粒子水平上，辐射衰变也会导致过冲。在这种情况下，过冲的幅度强烈地取决于温度以及材料的掺杂分数。如果超越单粒子水平的多体效应变得重要，以至于需要量子动力学描述，那么自旋过冲已经出现，而没有辐射衰减，并且对系统参数的变化更加鲁棒。我们表明，自旋过冲的起源可以通过其温度依赖性或通过其行为不同的掺杂分数来确定。只要存在辐射衰减和自旋翻转机制，这些结果可以预期适用于广泛的半导体。
We investigate the origin of overshoots in the exciton spin dynamics after resonant optical excitation. As a material system, we focus on diluted magnetic semiconductor quantum wells as they provide a strong spin-flip scattering for the carriers. Our study shows that overshoots can appear as a consequence of radiative decay even on the single-particle level in a theory without any memory. The magnitude of the overshoots in this case depends strongly on the temperature as well as the doping fraction of the material. If many-body effects beyond the single-particle level become important so that a quantum-kinetic description is required, a spin overshoot appears already without radiative decay and is much more robust against variations of system parameters. We show that the origin of the spin overshoot can be determined either via its temperature dependence or via its behavior for different doping fractions. The results can be expected to apply to a wide range of semiconductors as long as radiative decay and a spin-flip mechanism are present.