Complex coincidence of superconducting and inverse proximity in quasi 2D nanostructured SnTe

Abstract

Inducing superconductivity in Topological insulators (TIs) and Topological crystalline insulators (TCI) is being investigated rigorously as a promising strategy to take the quantum spintronic applications to the next level. In this work, a complex interplay between topological and superconducting components is carefully tuned in such a way that an unusual coincidence of superconducting and inverse proximity is captured for the first time in electrical transport properties of Quasi 2-dimentional nanostructured SnTe contacted using “s-wave’’ superconducting electrodes. Ultralow temperature measurements in the complex superconducting proximity phase reveals two critical fields (Hc2) of 0.9T and 510 Oe. Lower Hc2 is identified to be from the superconducting electrode while the higher one is attributed to the Interface. The presence (absence) of coincidence between upper critical field (HC2) extracted from Ginzburg Landau (GL) theory and Werthamer Helfand Hohenberg (WHH) plot in normal (inverse) superconducting proximity region and concurrent crossover in correlation lengths ξ(T) and Lϕ(T) are observed to be the manifestation of robust competition between the mutual domination of different mechanisms such as topological surface states and cooper pair correlations. The current dependent MR measurements clearly demonstrate the dominant role played by an interplay between the superconducting correlations and spin-orbit coupling. Interestingly, mere doubling of contact area of superconductor is observed to simultaneously enhance the critical field to ~4 T and transition temperature to ~4.1 K in the interface region is assuring the possibility of opening-up a new gate way in nano-topological-superconducting- spintronic applications.