Disorder-induced transition from type-I to type-II superconductivity in the Dirac semimetal PdTe₂

We report a doping study directed to intentionally induce disorder in PdTe₂ by the isoelectronic substitution of Pt. Two single-crystalline batches Pd_1-xPt_xTe₂ have been prepared with nominal doping concentrations x = 0.05 and x =0 .10. Sample characterization by energy dispersive x-ray spectroscopy revealed Pt did not dissolve homogeneously in the crystals. For the nominal value x = 0.10 small single crystals cut from the batch appeared to have x =0 .09, as well as the nonstoichiometric composition Pd_0.97 Pt<0.004 Te_2.03. Magnetic and heat capacity measurements demonstrate a transition from type-I to type-II superconducting behavior upon increasing disorder. From transport measurements we calculate a residual resistivity ρ0 = 1.4 μΩ cm suffices to turn PdTe₂ into a superconductor of the second kind.