title: Phase diagram of the layered oxide SnO: GW and electron-phonon studies.
abstract: 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 Tc 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 Tc 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 Tc 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.
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.|Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan and National Taiwan University, Taipei 10617, Taiwan.|Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Peng-Jen
authors.initials: PJ
authors.lastname: Chen
authors.affiliation: Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.|Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Horng-Tay
authors.initials: HT
authors.lastname: Jeng