Revealing hidden spin-momentum locking in a high-temperature cuprate superconductor
Revealing hidden spin-momentum locking in a high-temperature cuprate superconductor
复制标题
揭示高温铜酸盐超导体中隐藏的自旋动量锁定
DOI：
10.1126/science.aao0980
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发表时间：
2018-12-14
期刊：
影响因子：
56.9
通讯作者：
Lanzara, Alessandra
中科院分区：
文献类型：
--
作者：
Gotlieb, Kenneth;Lin, Chiu-Yun;Lanzara, Alessandra
揭示铜氧化物中的自旋-轨道耦合自旋和轨道自由度之间的强耦合在拓扑绝缘体的奇异能带结构的产生中是至关重要的。自旋-轨道耦合与电子关联的结合可能导致奇异效应;然而，这两种类型的相互作用很少在同一材料中被发现是强的。Gotlieb等人使用自旋和角度分辨光电子能谱来绘制铜氧化物Bi 2212的自旋织构。令人惊讶的是，他们发现了自旋-动量锁定的特征，与拓扑绝缘体中看到的没有什么不同。因此，除了强的电子相关性之外，这种铜氧化物还具有相当大的自旋轨道耦合。自旋和角度分辨光电子能谱揭示了铜氧化物Bi 2212中丰富的自旋结构。铜氧化物超导体长期以来被认为具有很强的电子相关性，但可以忽略自旋轨道耦合。使用自旋和角度分辨的光电子能谱，我们发现，研究最多的铜酸盐超导体之一，Bi 2212，具有非平凡的自旋纹理与自旋动量锁定，环绕布里渊区中心和自旋层锁定，允许相反的自旋状态被本地化在单位单元的不同部分。我们的研究结果对绝大多数铜氧化物模型提出了挑战，例如Hubbard模型及其变体，其中自旋-轨道相互作用大多被忽略，并打开了一个有趣的问题，即高温超导态如何在这种非平凡的自旋纹理存在下出现。
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.