Anomalous transport properties in Nb/Bi1.95Sb0.05Se3 hybrid structure

TL;DR

This study investigates the unique magnetotransport properties of a Nb/Bi1.95Sb0.05Se3 heterostructure, revealing anomalous resistance behaviors and potential spin-dependent scattering effects at low temperatures.

Contribution

It demonstrates proximity-induced anomalous transport phenomena in a Nb top superconductor and a topological insulator heterostructure, highlighting directional dependence of resistance below the superconducting transition.

Findings

Observation of Subnikov de Haas oscillations in TI region.

Anomalous linear resistance change in superconducting state.

Directional dependence of resistance below Tc indicating spin-dependent scattering.

Abstract

We report the proximity induced anomalous transport behavior in a Nb Bi1.95Sb0.05Se3 heterostructure. Mechanically Exfoliated single crystal of Bi1.95Sb0.05Se3 topological insulator (TI) is partially covered with a 100 nm thick Niobium superconductor using DC magnetron sputtering by shadow masking technique. The magnetotransport (MR) measurements have been performed simultaneously on the TI sample with and without Nb top layer in the temperature,T, range of 3 to 8 K, and a magnetic field B up to 15 T. MR on TI region shows Subnikov de Haas oscillation at fields greater than 5 T. Anomalous linear change in resistance is observed in the field range of negative 4T to positive 4T at which Nb is superconducting. At 0 T field, the temperature dependence of resistance on the Nb covered region revealed a superconducting transition (TC) at 8.2 K, whereas TI area showed similar TC with the absence of zero resistance states due to the additional resistance from superconductor (SC) TI interface. Interestingly below the TC the R vs T measured on TI showed an enhancement in resistance for positive field and prominent fall in resistance for negative field direction. This indicates the directional dependent scattering of the Cooper pairs on the surface of the TI due to the superposition of spin singlet and triplet states in the superconductor and TI respectively.