Investigation of superconductivity and magnetoresistance in polycrystalline SnTe thin films
Phuoc Huu Le1,2*, Wen-Yen Tzeng1, Chih Wei Luo1, Jiunn-Yuan Lin3, Kaung Hsiung Wu1
1Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2Faculty of Basic Sciences, Can Tho University of Medicine and Pharmacy, Can Tho, Viet Nam
3Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan
* presenting author:Phuoc Le,
SnTe is a topological crystalline insulator (TCI) that possesses spin-polarized and multiple Dirac-dispersive surface states protected by crystal symmetry. The superconductivity in a TCI (i.e. SnTe) has become important as it is a candidate of topological superconductivity, but it’s superconducting and magnetoresistance characteristics are poorly understood. In this study, p-type SnTe thin films were grown on insulating sapphire (0001) substrates by pulsed laser deposition. Films grown at substrate temperatures Ts ≥ 300 °C presented the superconductivity with onset critical temperature (Tc) of approximately 3.8 K; meanwhile, those grown at Ts ≤ 250°C showed the normal semiconducting behaviors in ρ(T) curves. The onset Tc decreased from 3.8 to 3.1 K with increasing magnetic fields from 0 to 2 kOe, indicating the transitions are superconducting in nature. The detailed investigation suggests the existence of pure Sn-inclusions naturally segregated to the surfaces which induce the superconductivity. Moreover, the existence of superconducting regions at the Sn/SnTe interfaces is suggested. In addition, the magnetoresistivity (MR) at temperatures below the superconducting transitions showed the anomalous “bell” shapes, which originate from the superconducting transitions. The MR characteristics in SnTe films with different thicknesses have investigated and discussed in details.

Keywords: superconductivity, magnetoresistivity, SnTe, Topological crystalline insulator