Thickness Dependence of Superconductivity in Layered Topological Superconductor β-PdBi₂

We report a systematic study on the thickness-dependent superconductivity and transport properties in exfoliated layered topological superconductor β-PdBi₂. The superconducting transition temperature T_c is found to decrease with the decreasing thickness. Below a critical thickness of 45 nm, the superconductivity is suppressed, but followed by an abrupt resistance jump near T_c, which is in opposite to the behavior in a superconductor. We attribute suppressed T_c to the enhanced disorder as the thickness decreases. The possible physical mechanisms were discussed for the origination of sharply increased resistance in thinner β-PdBi₂ samples.