Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 62: Focus Session: High Temperature Superconductivity in Hydrides
TT 62.4: Hauptvortrag
Donnerstag, 10. März 2016, 11:15–11:45, H20
Strong-Coupling Electron-Phonon Superconductivity in H3S — •Warren E. Pickett1 and Yundi Quan2 — 1University of California Davis, Davis CA, USA — 2Beijing Normal University, Beijing, China
The superconducting phase of hydrogen sulfide at Tc = 200 K observed by Eremets’ group at pressures around 200 GPa is simple bcc Im-3m H3S. Remarkably, this record high temperature superconductor was predicted beforehand by Duan et al., so the theory would seem to be in place. Here we will discuss why this is not true. Several extremes are involved: extreme pressure, meaning reduction of volume;extremely high H phonon energy scale around 1400 K; unusually narrow peak in the density of states at the Fermi level; extremely high temperature for a superconductor. Analysis of the H3S electronic structure and two important van Hove singularities (vHs) reveal the effect of sulfur. The implications for the strong coupling Migdal-Eliashberg theory will be discussed. followed by comments on ways of increasing Tc in H3S-like materials.