Speaker

王天淳

东京大学

Date＆Time

2022.03.01（Tues）AM 10:00

Location

Aoqing Tang Building B52

Reporter

       王天淳，2018年本科毕业于复旦大学物理系。2018年至今在东京大学工学系物理工学研究科攻读博士学位。2018年起加入导师Ryotaro Arita教授的课题组。主要研究方向为应用第一性原理计算方法对材料性质进行模拟和预测。目前的研究课题包括Migdal-Eliashberg理论框架下的超导温度计算方法开发，以及对高压氢化物超导体系的计算和预测。

Abstract

Recently, it has been reported that room-temperature superconductivity with Tc ~ 280 K emerges in carbonaceous sulfur hydride (C-S-H) systems under high pressure up to 270 GPa [1]. Since their atomic configuration is still not determined, we explore a variety of crystal structures in a C-S-H convex hull and discuss the stability of candidate structures of C-S-H ternary compounds [2].

In this study, we show that the same theoretical tools that successfully explain other hydride systems under pressure seem to be at odds with the recently claimed conventional room-temperature superconductivity of carbonaceous sulfur hydride. We support our conclusions with (i) the absence of a dominant low-enthalpy stoichiometry and crystal structure in the ternary phase diagram. (ii) Only the thermodynamics of C-doping phases appears to be marginally competing in enthalpy against H3S. (iii) Accurate results of the transition temperature given by ab initio Migdal-Eliashberg calculations [3] differ by more than 110 K from recent theoretical claims explaining the high-temperature superconductivity in carbonaceous hydrogen sulfide. An unconventional mechanism of superconductivity or a breakdown of current theories in this system is possibly behind the disagreement.

[1] E. Snider, N. Dasenbrock-Gammon, R. Mcbride, M. Debessai, H. Vindana, K. Vencatasamy, K. V. Lawler, A. Salamat and R. P. Dias, Nature 586, 373-377 (2020)

[2] T. Wang, M. Hirayama, T. Nomoto, T. Koretsune, R. Arita, and José A. Flores-Livas, Phys. Rev. B 104, 064510 (2021)

[3] T. Wang, T. Nomoto, Y. Nomura, H. Shinaoka, J. Otsuki, T. Koretsune and R. Arita, Phys. Rev. B 102, 134503 (2020)