Non-Monotonic Behavior of the Critical Field of Superconducting PdTe₂ thin films.

Few-layer PdTe₂ is reported to be a Type-II Ising superconductor. Its upper critical field can exceed the Pauli limit by more than 7 times.[1] We achieve the synthesis of wafer scale superconducting PdTe₂ thin films synthesized using a two-setp Chemical Vapor Deposition process. We report on four samples with different thickness spanning 50 nm to 25 nm. X-ray diffraction analysis shows that there are two crystal orientation (001), (011) in the samples. The critical temperature is found to be around 1.4 K and does not depend on the thickness. We have then conducted magnetotransport measurement down to 20 mK and extracted both the in-plane and out-of-plane upper critical field H_C2. H_C2 in the in-plane direction shows non-monotonic trends at low temperatures indicating the presence of Rashba and Ising orbital coupling with the former caused by broken inversion symmetry. H_C2 in the out-of-plane direction shows an upturn at low temperature likely from a two- band contribution to the superconducting states. These results improve our understanding of the Rashba and Ising spin orbit coupling in layered superconductors. [1] Yi Liu, Nanolett. 20 5728 (2020).