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

摘要

PtBi2 is a Weyl semimetal, which demonstrates superconductivity with low critical temperature T-c similar to 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 present the observation of PC enhanced superconductivity. We show that the Yanson's 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 T-c up to similar to 3.5 K in PCs. The observed T-c 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 T-c is 3.5 K, which corresponds to the experimental value. Published under an exclusive license by AIP Publishing.