Phase diagram of the layered oxide SnO: GW and electron-phonon studies

• Published in: Scientific reports Vol. 5; no. 1; p. 16359
• Main Authors: Chen, Peng-Jen, Jeng, Horng-Tay
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.11.2015; Nature Publishing Group
• Subjects: 639/766/119/1003; 639/766/119/995; Crystal structure; Humanities and Social Sciences; multidisciplinary; Phase transitions; Physics; Pressure; Science; Semiconductors
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep16359

First-principles calculations are performed to study the electronic properties and the electron-phonon interactions of the layered oxide semiconductor SnO. In addition to the high hole mobility that makes SnO a promising material in electronics, it has recently been reported that the semimetallic phase under pressure is superconducting. The superconducting T c curve exhibits a dome-like feature under pressure and reaches the maximum of 1.4 K at p  = 9.2 GPa. Both its crystal structure and the dome-like T c curve are reminiscent of the Fe-based superconductor FeSe. Motivated by this observation, we investigate the electronic, phonon and their interactions in SnO using first-principles schemes. GW approximation is adopted to correct the underestimated band gaps, including real and continuous band gaps in the semiconducting and semimetallic phases. The phase diagram showing the semiconductor-to-semimetal transition and the T c curve has been successfully reproduced. Detailed analysis of the electron-phonon interactions demonstrate the importance of the out-of-plane motions of O atoms and the Sn- s lone pairs for the superconductivity to occur. Our method combining GW and e-ph calculations can be further extended to the study of other materials that undergo insulator-to-superconductor phase transition.