Revealing spin-orbit coupling in a cuprate Strong coupling between the spin and orbital degrees of freedom is crucial in generating the exotic band structure of topological insulators. The combination of spin-orbit coupling with electronic correlations could lead to exotic effects; however, these two types of interactions are rarely found to be strong in the same material. Gotlieb et al. used spin- and angle-resolved photoemission spectroscopy to map out the spin texture in the cuprate Bi2212. Surprisingly, they found signatures of spin-momentum locking, not unlike that seen in topological insulators. Thus, in addition to strong electronic correlations, this cuprate also has considerable spin-orbit coupling. Science, this issue p. 1271 Spin- and angle-resolved photoemission spectroscopy reveals a rich spin texture in the cuprate Bi2212. Cuprate superconductors have long been thought of as having strong electronic correlations but negligible spin-orbit coupling. Using spin- and angle-resolved photoemission spectroscopy, we discovered that one of the most studied cuprate superconductors, Bi2212, has a nontrivial spin texture with a spin-momentum locking that circles the Brillouin zone center and a spin-layer locking that allows states of opposite spin to be localized in different parts of the unit cell. Our findings pose challenges for the vast majority of models of cuprates, such as the Hubbard model and its variants, where spin-orbit interaction has been mostly neglected, and open the intriguing question of how the high-temperature superconducting state emerges in the presence of this nontrivial spin texture.

中文翻译：

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揭示高温铜酸盐超导体中隐藏的自旋动量锁定

揭示铜酸盐中的自旋轨道耦合自旋和轨道自由度之间的强耦合对于生成拓扑绝缘体的奇异能带结构至关重要。自旋轨道耦合与电子相关性的结合可能会导致奇异效应；然而，很少发现这两种类型的相互作用在同一种材料中很强。戈特利布等人。使用自旋和角度分辨光电子能谱来绘制铜酸盐 Bi2212 中的自旋结构。令人惊讶的是，他们发现了自旋动量锁定的特征，这与在拓扑绝缘体中看到的不同。因此，除了强电子相关性之外，这种铜酸盐还具有相当大的自旋轨道耦合。科学，这个问题 p。1271 自旋和角分辨光电子能谱揭示了铜酸盐 Bi2212 中丰富的自旋结构。长期以来，铜酸盐超导体被认为具有很强的电子相关性，但自旋轨道耦合可以忽略不计。使用自旋和角分辨光电子能谱，我们发现研究最多的铜酸盐超导体之一 Bi2212 具有非平凡的自旋纹理，具有环绕布里渊区中心的自旋动量锁定和允许状态的自旋层锁定相反的自旋定位在晶胞的不同部分。我们的发现对绝大多数铜酸盐模型提出了挑战，例如哈伯德模型及其变体，其中自旋轨道相互作用大多被忽略，并打开了高温超导状态如何在存在的情况下出现的有趣问题这种非平凡的旋转纹理。