Multigap nodeless superconductivity in the Dirac semimetal PdTe

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 the point-contact spectroscopy (PCS) method to systematically study the superconducting gap in PdTe single crystals with a SC transition temperature ${T}_{c}=4.3\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. 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 ${\mathrm{\ensuremath{\Delta}}}_{L}$ with $2{\mathrm{\ensuremath{\Delta}}}_{L}=3.7\phantom{\rule{0.28em}{0ex}}{k}_{B}{T}_{c}$ and the smaller gap ${\mathrm{\ensuremath{\Delta}}}_{S}$ yielding $2{\mathrm{\ensuremath{\Delta}}}_{S}=1.1\ensuremath{-}2.2\phantom{\rule{0.28em}{0ex}}{k}_{B}{T}_{c}$ 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.