Interplay between topological insulators and superconductors

TL;DR

This study investigates the electronic transport properties of Bi2Se3 topological insulator thin films in contact with superconducting electrodes, revealing a complex interplay affecting both the film's resistance and the electrodes' superconductivity.

Contribution

It provides detailed experimental insights into the interaction between topological surface states and superconductivity in hybrid structures.

Findings

Superconducting electrodes cause an abrupt resistance increase in Bi2Se3 films.

Superconductivity in electrodes is weakened when in contact with the topological insulator.

Evidence suggests coupling between Cooper pairs and spin-polarized surface states.

Abstract

Topological insulators are insulating in the bulk but possess metallic surface states protected by time-reversal symmetry. Here, we report a detailed electronic transport study in high quality Bi2Se3 topological insulator thin films contacted by superconducting (In, Al and W) electrodes. The resistance of the film shows an abrupt and significant upturn when the electrodes become superconducting. In turn, the Bi2Se3 film strongly weakens the superconductivity of the electrodes, significantly reducing both their transition temperatures and critical fields. A possible interpretation of these results is that the superconducting electrodes are accessing the surface states and the experimental results are the consequence of the interplay between the Cooper pairs of the electrodes and the spin polarized current of the surface states in Bi2Se3.