SPring-8, the large synchrotron radiation facility

Speaker : Dr. Mikhail I. Eremets

Language : English

Affiliation : Max-Planck Institut fur Chemie, Chemistry and Physics at High Pressures Group

Title : Conventional superconductivity at 195 K in hydrogen sulfide at high pressures

Abstract:
The Bardeen-Cooper-Schrieffer (BCS) theory gives a guide for achieving high T_c: it should be a favorable combination of high frequency phonons, strong coupling between electrons and phonons, and high density of states. These conditions can be fulfilled for metallic hydrogen and covalent hydrogen dominant compounds. We found that sulfur hydride transforms at P~90 GPa to metal and superconductor with the record critical temperature of superconductivity (T_c) of 195 K at P~150 GPa (arXiv:1412.0460). This superconductivity is likely related to higher hydrides H_nS (n>2) formed due to the dissociation of H₂S. We proved occurrence of superconductivity by the sharp drop of the resistivity at least 50 times lower than the copper resistivity and the decrease of T_c with magnetic field. The isotope shift of T_c in D₂S consists with predictions of the BCS theory and indicates a major role of phonons in the superconductivity.

This seminar was supported by JSPS KAKENHI Grant Number 26000006.

Organizer : Yasuo Ohishi
Mail : ohishi@spring8.or.jp
PHS : 3904