Type-I superconductivity in the Dirac semimetal PdTe2

The superconductor PdTe2 was recently classified as a type-II Dirac semimetal, and advocated to be an improved platform for topological superconductivity. Here, we report magnetic and transport measurements conducted to determine the nature of the superconducting phase. Surprisingly, we find that PdTe2 is a type-I superconductor with Tc=1.64 K and a critical field μ0Hc(0)=13.6 mT. Our crystals also exhibit the intermediate state as demonstrated by the differential paramagnetic effect. For H>Hc we observe superconductivity of the surface sheath. This calls for a close examination of superconductivity in PdTe2 in view of the presence of topological surface states.