Odd-frequency superconductivity and Meissner effect in the doped topological insulator Bi$_2$Se$_3$

TL;DR

This paper investigates the unconventional odd-frequency superconductivity in doped Bi$_2$Se$_3$, revealing dominant odd-frequency pairing and a diamagnetic Meissner effect driven by inter-band contributions.

Contribution

It classifies all superconducting pair correlations in doped Bi$_2$Se$_3$ and uncovers the dominance of odd-frequency pairing and its unusual diamagnetic Meissner response.

Findings

Intra-orbital odd-frequency pairing dominates over a broad frequency range.

Inter-band contributions lead to a diamagnetic odd-frequency Meissner effect.

Superconducting correlations are classified comprehensively in doped Bi$_2$Se$_3$.

Abstract

Doped Bi$_2$Se$_3$ is proposed to be a nematic superconductor originating from unusual inter-orbital pairing. We classify all induced superconducting pair correlations in Bi$_2$Se$_3$ and discover that intra-orbital odd-frequency pairing dominates over a significant range of frequencies. Moreover, we explore the contributions of even- and odd-frequency pairing to the Meissner effect, including separating intra- and inter-band processes in the response function. Contrary to expectations, and due to inter-band contributions, we find a diamagnetic odd-frequency Meissner effect.