Direct evidence of hidden local spin polarization in a centrosymmetric superconductor LaO0.55 F0.45BiS2

• Published in: Nature communications Vol. 8; no. 1; pp. 1 - 7
• Main Authors: Wu, Shi-Long, Sumida, Kazuki, Miyamoto, Koji, Taguchi, Kazuaki, Yoshikawa, Tomoki, Kimura, Akio, Ueda, Yoshifumi, Arita, Masashi, Nagao, Masanori, Watauchi, Satoshi, Tanaka, Isao, Okuda, Taichi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.12.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/1001; 639/766/119/1003; 639/766/119/2792; 639/766/119/995; Asymmetry; Band structure of solids; Coexistence; Conduction; Conduction bands; Electron spin; Electrons; Fabrication; Field effect transistors; Humanities and Social Sciences; multidisciplinary; Photoelectric emission; Polarization; Polarization (spin alignment); Science; Science (multidisciplinary); Spectroscopy; Superconductivity; Valence band
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-02058-2

Conventional Rashba spin polarization is caused by the combination of strong spin–orbit interaction and spatial inversion asymmetry. However, Rashba–Dresselhaus-type spin-split states are predicted in the centrosymmetric LaOBiS 2 system by recent theory, which stem from the local inversion asymmetry of active BiS 2 layer. By performing high-resolution spin- and angle-resolved photoemission spectroscopy, we have investigated the electronic band structure and spin texture of superconductor LaO 0.55 F 0.45 BiS 2 . Here we present direct spectroscopic evidence for the local spin polarization of both the valence band and the conduction band. In particular, the coexistence of Rashba-like and Dresselhaus-like spin textures has been observed in the conduction band. The finding is of key importance for fabrication of proposed dual-gated spin-field effect transistor. Moreover, the spin-split band leads to a spin–momentum locking Fermi surface from which superconductivity emerges. Our demonstration not only expands the scope of spintronic materials but also enhances the understanding of spin–orbit interaction-related superconductivity. The local broken symmetry induced spin-splitting in centrosymmetric materials has been predicted previously. Here the authors provide spectroscopic evidence for the coexistence of Rashba-like and Dresselhaus-like spin textures in centrosymmetric electron doped superconductor La(O,F)BiS 2 .