Multigap nodeless superconductivity in Dirac semimetal PdTe

TL;DR

This study uses point-contact spectroscopy to reveal multigap nodeless superconductivity in PdTe, a Dirac semimetal, showing two distinct superconducting gaps with weak interband scattering, indicating complex Fermi surface anisotropy.

Contribution

It provides the first systematic spectroscopic evidence of multigap nodeless superconductivity in PdTe, a Dirac semimetal, using a two-gap model fitting.

Findings

Identification of two superconducting gaps in PdTe.

Weak interband scattering observed among different contacts.

Fermi surface anisotropy influences conductance spectra variations.

Abstract

PdTe has recently been reported to be a type-II Dirac semimetal while a bulk nodal and surface nodeless superconductivity (SC) has been claimed to coexist. In this work, we applied point-contact spectroscopy (PCS) method to systematically study the superconducting gap in PdTe single crystals with a SC transition temperature $T_{c}=4.3$ K. The obtained differential conductance curves show a common deviation from a single-gap superconducting behavior and can be better fitted by a two-gap Blonder-Tinkham-Klapwijk model, suggesting the larger gap $\Delta_{L}$ with $2\Delta_{L}$=3.7 $k_{B}T_{c}$ and the smaller gap $\Delta_S$ yielding $2\Delta_{S}$=1.1-2.2 $k_{B}T_{c}$ with a weak interband scattering. The variations of conductance spectra among different contacts are proposed to be caused by the anisotropy of Fermi surface topology associated with different gaps.