Hybrid organic–inorganic perovskites have emerged as a new class of semiconductors that exhibit excellent performance as active layers in photovoltaic solar cells. These compounds are also highly promising materials for the field of spintronics due to their large and tunable spin–orbit coupling, spin-dependent optical selection rules, and their predicted electrically tunable Rashba spin splitting. Here we demonstrate the optical orientation of excitons and optical detection of spin-polarized exciton quantum beating in polycrystalline films of the hybrid perovskite CH₃NH₃PbCl_xI_3−x. Time-resolved Faraday rotation measurement in zero magnetic field reveals unexpectedly long spin lifetimes exceeding 1 ns at 4 K, despite the large spin–orbit couplings of the heavy lead and iodine atoms. The quantum beating of exciton states in transverse magnetic fields shows two distinct frequencies, corresponding to two g-factors of 2.63 and −0.33, which we assign to electrons and holes, respectively. These results provide a basic picture of the exciton states in hybrid perovskites, and suggest they hold potential for spintronic applications.

中文翻译：

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有机-无机杂化钙钛矿中的自旋极化激子量子跳动

杂化有机-无机钙钛矿已经成为一类新型的半导体，在光伏太阳能电池中作为活性层表现出出色的性能。这些化合物由于其大而可调的自旋-轨道耦合，自旋相关的光学选择规则以及可预测的电可调Rashba自旋分裂，也是自旋电子学领域极有希望的材料。在这里，我们展示了钙钛矿杂化钙钛矿CH ₃ NH ₃ PbCl _x I _{3- x的}多晶膜中激子的光学取向和自旋极化激子量子拍打的光学检测。时间分辨的法拉第旋转在零磁场中的测量显示出意外的超长自旋寿命， 在4时超过1 ns 尽管重铅和碘原子之间存在很大的自旋轨道耦合，但K仍然存在。横向磁场中激子态的量子跳动显示了两个不同的频率，分别对应于我们分别分配给电子和空穴的两个g因子2.63和-0.33。这些结果提供了混合钙钛矿中激子态的基本图片，并表明它们具有自旋电子学应用的潜力。