Effect of covalent bonding on the superconducting critical temperature of the H-S-Se system

Binbin Liu, Wenwen Cui, Jingming Shi, Li Zhu, Ju Chen, Shuyi Lin, Ruiming Su, Jiayu Ma, Kang Yang, Meiling Xu, Jian Hao, Artur P. Durajski, Jingshan Qi, Yanling Li, and Yinwei Li
Phys. Rev. B 98, 174101 – Published 1 November 2018

Abstract

Hydrogen-rich materials have attracted great interest since the recent discovery of superconductivity at 203 K in highly compressed hydrogen sulfide. To probe the role of covalent bonding in determining the Tc of hydrogen-related superconductors, we systematically studied the crystal structure and superconductivity of H6SSe, a hypothetical compound derived from H3S with half its S atoms replaced by group neighbor Se. First-principles structure searches identify three dynamically stable structures for H6SSe at 200 GPa. Interestingly, all three structures keep the main feature of the cubic Im3¯m structure of H3S, but with different Se substitution positions. Electron-phonon coupling calculations reveal the superconductive potential of the three phases of H6SSe, with Tc decreasing (from 195 to 115 K) upon the declining strength of the weakest covalent H-S or H-Se bonds in each structure, thereby highlighting the key role of covalent bonding in determining Tc. For comparison, O-substituted H6SO was predicted to assume a semiconducting phase with entirely different structural features from H6SSe. We attribute this difference to the much stronger electronegativity of O (3.44) compared with S (2.58) or Se (2.55).

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  • Received 8 June 2018
  • Revised 29 September 2018

DOI:https://doi.org/10.1103/PhysRevB.98.174101

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Binbin Liu1, Wenwen Cui1,*, Jingming Shi1, Li Zhu2, Ju Chen1, Shuyi Lin1, Ruiming Su1, Jiayu Ma1, Kang Yang1, Meiling Xu1, Jian Hao1, Artur P. Durajski3, Jingshan Qi1, Yanling Li1, and Yinwei Li1,†

  • 1School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
  • 2Extreme Materials Initiative, Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, D.C. 20015, USA
  • 3Institute of Physics, Czȩtochowa University of Technology, Aleja Armii Krajowej 19, 42-200 Czȩstochowa, Poland

  • *wenwencui@jsnu.edu.cn
  • yinwei_li@jsnu.edu.cn

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Issue

Vol. 98, Iss. 17 — 1 November 2018

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