Multiband superconductivity in high pressure sulfur hydrides

TL;DR

This study investigates multiband superconductivity in pressurized H_3S at 155 GPa, revealing two distinct superconducting gaps and their temperature dependence, supported by Eliashberg theory analysis, indicating complex pairing mechanisms.

Contribution

The paper demonstrates the presence of two superconducting gaps in H_3S and models their behavior using two-band Eliashberg theory, highlighting the importance of inter-band interactions.

Findings

Identification of two distinct superconducting gaps in H_3S.

Prediction of different temperature dependencies for each gap.

Evidence supporting multiband superconductivity in high-pressure sulfur hydrides.

Abstract

The temperature dependence of the two superconducting gaps in pressurised H_3S at 155 GPa with a critical temperature of 203 K has been determined by data analysis of the experimental curve of the upper critical magnetic field as a function of temperature in the framework of the two bands s-wave Eliashberg theory, with two different phonon mediated intra-band Cooper pairing channels in a regime of moderate strong couplings with the key role of the pair exchange interaction between the two gaps giving the two non-diagonal terms of the coupling tensor which are missing in the single band s wave Eliashberg theory. The results provide the prediction of the different temperature dependence of the small and large gaps as a function of temperature which provide evidence of multi-gap superconductivity in H_3S.