Evidence for singular-phonon-induced nematic superconductivity in a topological superconductor candidate Sr0.1Bi2Se3

• Published in: Nature communications Vol. 10; no. 1; pp. 1 - 6
• Main Authors: Wang, Jinghui, Ran, Kejing, Li, Shichao, Ma, Zhen, Bao, Song, Cai, Zhengwei, Zhang, Youtian, Nakajima, Kenji, Ohira-Kawamura, Seiko, Čermák, P., Schneidewind, A., Savrasov, Sergey Y., Wan, Xiangang, Wen, Jinsheng
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.06.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/1003; 639/766/119/995; Copper; Electron phonon interactions; Humanities and Social Sciences; Inelastic scattering; multidisciplinary; Neutron scattering; Neutrons; Niobium; Phonons; Science; Science (multidisciplinary); Single crystals; Superconductivity; Topological superconductors; Wavelengths
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-10942-2

Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent s -wave pairing function, due to the isotropic interactions between electrons and phonons along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr 0.1 Bi 2 Se 3 , a prime candidate for realizing topological superconductivity by doping the topological insulator Bi 2 Se 3 , we find that there exist highly anisotropic phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the [001] direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic p -wave nematic superconducting pairing in the M x Bi 2 Se 3 (M = Cu, Sr, Nb) superconductor family. Therefore, we show these superconductors to be example systems where electron-phonon interaction can induce more exotic superconducting pairing than the s -wave, consistent with the topological superconductivity. Superconductivity mediated by phonons is usually conventional due to isotropic electron-phonon coupling. Here, Wang et al. report highly anisotropic phonons only along [001] direction in Sr 0.1 Bi 2 Se 3 , indicating a singular electron-phonon coupling which favors a p -wave nematic superconductivity scenario.