Revealing hidden spin-momentum locking in a high-temperature cuprate superconductor

• Published in: Science (American Association for the Advancement of Science) Vol. 362; no. 6420; pp. 1271 - 1275
• Main Authors: Gotlieb, Kenneth, Lin, Chiu-Yun, Serbyn, Maksym, Zhang, Wentao, Smallwood, Christopher L, Jozwiak, Christopher, Eisaki, Hiroshi, Hussain, Zahid, Vishwanath, Ashvin, Lanzara, Alessandra
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 14-12-2018
• Subjects: Brillouin zones; Correlation; Cuprates; Electron spin; High temperature; Locking; Momentum; Photoelectric emission; Photoelectron spectroscopy; Spectroscopy; Spectrum analysis; Spin-orbit interactions; Texture; Topological insulators; Unit cell
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aao0980

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.