Superconductivity in three-dimensional interacting doped topological insulators

TL;DR

This paper uses renormalization group analysis to show that doped three-dimensional topological insulators with interactions tend to develop scalar s-wave and pseudoscalar p-wave superconducting pairings, regardless of Fermi surface topology.

Contribution

It provides a theoretical framework demonstrating the emergence of specific superconducting pairings in doped topological insulators due to electron interactions.

Findings

Propensity for s-wave and p-wave pairing in doped topological insulators.

Superconductivity can arise irrespective of Fermi surface topology.

Theoretical basis applicable to doped narrow gap semiconductors.

Abstract

Three-dimensional doped Dirac insulators foster simply connected (in both topological and trivial regimes) and annular (deep inside the topological regime) Fermi surfaces (FSs) in the normal state, and allow on-site repulsions among fermions with opposite spin ($U_1$) and parity ($U_2$) eigenvalues. From an unbiased leading-order (one-loop) renormalization group analysis, controlled by a suitable $\epsilon$ expansion, we show that this system develops a strong propensity toward the nucleation of scalar $s$-wave and odd-parity pseudoscalar $p$-wave pairings, favored by repulsive $U_1$ and $U_2$ interactions, respectively, irrespective of the underlying FS topology. Our results can be pertinent for the observed superconductivity in various doped narrow gap semiconductors, and the theoretical foundation can readily be applied to investigate similar phenomenon in various doped topological materials.