Robust two-dimensional superconductivity and vortex system in Bi2Te3/FeTe heterostructures

TL;DR

This study demonstrates the robustness of two-dimensional superconductivity and vortex dynamics in Bi2Te3/FeTe heterostructures, even after two years of air exposure, highlighting potential for Majorana fermion research.

Contribution

It provides new insights into the stability of interfacial superconductivity and vortex behavior in Bi2Te3/FeTe heterostructures over time and under varying conditions.

Findings

Superconductivity remains robust after two years of air exposure.

A new feature at ~13 K appears in aged samples, related to superconductivity.

Resistance follows Arrhenius behavior indicating thermally activated flux flow.

Abstract

The discovery of two-dimensional superconductivity in Bi2Te3/FeTe heterostructure provides a new platform for the search of Majorana fermions in condensed matter systems. Since Majorana fermions are expected to reside at the core of the vortices, a close examination of the vortex dynamics in superconducting interface is of paramount importance. Here, we report the robustness of the interfacial superconductivity and 2D vortex dynamics in four as-grown and aged Bi2Te3/FeTe heterostructure with different Bi2Te3 epilayer thickness (3, 5, 7, 14 nm). After two years' air exposure, superconductivity remains robust even when the thickness of Bi2Te3 epilayer is down to 3 nm. Meanwhile, a new feature at ~13 K is induced in the aged samples, and the high field studies reveal its relevance to superconductivity. The resistance of all as-grown and aged heterostructures, just below the superconducting transition temperature follows the Arrhenius relation, indicating the thermally activated flux flow behavior at the interface of Bi2Te3 and FeTe. Moreover, the activation energy exhibits a logarithmic dependence on the magnetic field, providing a compelling evidence for the 2D vortex dynamics in this novel system. The weak disorder associated with aging-induced Te vacancies is possibly responsible for these observed phenomena.