Hybrid organic-inorganic perovskites (HOIPs) are prime candidates for studying Rashba effects due to the heavy metal and halogen atoms in their crystal structure coupled with predicted inversion symmetry breaking. Nevertheless, observation of the Rashba effect in cubic CH₃NH₃PbBr₃ single crystals that possess bulk inversion symmetry is the subject of extensive debate due to the lack of conclusive experiments and theoretical explanations. Here, we provide experimental evidence that Rashba state in cubic CH₃NH₃PbBr₃ single crystals at room temperature occurs exclusively on the crystal surface and depends on specific surface termination that results in local symmetry breaking. We demonstrate this using a suite of spatially resolved and depth-sensitive techniques, including circular photogalvanic effect, inverse spin Hall effect, and multiphoton microscopy, that are supported by first principle calculations. Our work suggests using surface Rashba states in these materials for spintronic applications.

中文翻译：

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CH3NH3PbBr3单晶表面空间分辨Rashba态的观察

杂化有机-无机钙钛矿 (HOIP) 是研究 Rashba 效应的主要候选材料，因为它们的晶体结构中含有重金属和卤素原子，再加上预测的反转对称性破坏。然而，由于缺乏结论性的实验和理论解释，在具有整体反转对称性的立方 CH ₃ NH ₃ PbBr ₃单晶中观察 Rashba 效应是一个广泛争论的主题。在这里，我们提供了实验证据表明Rashba在立方 CH ₃ NH ₃ PbBr _{3 中状态}室温下的单晶仅出现在晶体表面，取决于导致局部对称性破坏的特定表面终止。我们使用一套空间分辨和深度敏感的技术来证明这一点，包括圆形光电流效应、逆自旋霍尔效应和多光子显微镜，这些技术得到第一原理计算的支持。我们的工作建议在这些材料中使用表面 Rashba 态用于自旋电子应用。