Institut des NanoSciences de Paris, UPMC Université Paris 06, CNRS UMR 7588, 4 place Jussieu, F-75252 Paris Cedex 05, France.
J Phys Condens Matter. 2013 May 22;25(20):202202. doi: 10.1088/0953-8984/25/20/202202. Epub 2013 Apr 30.
The initialization of a resident hole spin by the absorption of a circularly polarized light at resonance involves the formation of an excited state called a trion state. For a pure heavy hole, this optical initialization is mediated by the hyperfine electron-nuclear coupling in the trion state. We show here that for a mixed-hole spin an additional mechanism for the optical initialization appears, associated to 'crossed transitions'; it becomes dominant and keeps a high level of hole spin polarization when the magnetic field screens the electron-nuclear interaction. Finally, using a simple model, we obtain a good theoretical agreement with pulsed pump-probe experiments.
通过在共振处吸收圆偏振光，可使局域空穴自旋初始化，这涉及到形成一个被称为三体态的激发态。对于纯重空穴而言，这种光初始化由三体态中的超精细电子-核耦合介导。我们在此表明，对于混合空穴自旋，出现了另一种光学初始化机制，与“交叉跃迁”有关；当磁场屏蔽电子-核相互作用时，它变得占主导地位，并保持高水平的空穴自旋极化。最后，我们使用一个简单的模型，与脉冲泵浦探测实验获得了很好的理论一致性。
