Electron-phonon interaction and point contact enhanced superconductivity in trigonal PtBi2

TL;DR

This study reveals that point contact spectroscopy uncovers enhanced superconductivity in PtBi2, with Tc increasing from 0.6 K to about 3.5 K due to electron-phonon interactions, supported by theoretical calculations.

Contribution

It demonstrates that point contact spectroscopy can significantly enhance and probe superconductivity in PtBi2, providing new insights into electron-phonon interactions in this material.

Findings

Point contact spectra show a broad maximum around 15 meV indicating EPI.

Superconducting transition temperature Tc increases to ~3.5 K in PCs.

Theoretical calculations agree with experimental Tc, confirming EPI's role.

Abstract

PtBi2 is a Weyl semimetal, which demonstrates superconductivity with low critical temperature Tc ~ 0.6 K in the bulk. Here, we report our study of electron-phonon interaction (EPI) in trigonal PtBi2 by the Yanson point contact (PC) spectroscopy and presenting the observation of PC enhanced superconductivity. We show, that the Yansons PC spectra display a broad maximum around 15 meV, indicating, apparently, EPI mechanism of Cooper pairing in PtBi2. Moreover, we discovered a substantial increase of Tc up to ~ 3.5 K in PCs. The observed Tc is sufficiently higher than the bulk value, as well as detected at hydrostatic pressure. We calculated the phonon density of states and Eliashberg EPI function in PtBi2 within the framework of the density functional theory. A comparison of experimental data with theoretical calculations showed acceptable agreement. The theoretical Tc is 3.5 K, which corresponds to the experimental value.