Emergence of Topological Superconductivity in Doped Topological Dirac Semimetals under Symmetry-Lowering Lattice Distortions

TL;DR

This paper theoretically investigates how symmetry-lowering lattice distortions in doped topological Dirac semimetals can induce unconventional, topologically nontrivial superconductivity with gapless surface states, aligning with recent experimental observations.

Contribution

It identifies specific lattice distortions that promote topological superconductivity and demonstrates their effect on critical temperature and surface states, providing a pathway for experimental control.

Findings

Lattice distortions induce unconventional superconductivity with gapless surface states.

Certain distortions lead to topological nodal or crystalline superconductivity.

Lattice distortions increase the superconducting critical temperature.

Abstract

Recently, unconventional superconductivity having a zero-bias conductance peak is reported in doped topological Dirac semimetal (DSM) with lattice distortion. Motivated by the experiments, we theoretically study the possible symmetry-lowering lattice distortions and their effects on the emergence of unconventional superconductivity in doped topological DSM. We find four types of symmetry-lowering lattice distortions that reproduce the crystal symmetries relevant to experiments from the group-theoretical analysis. Considering inter-orbital and intra-orbital electron density-density interactions, we calculate superconducting phase diagrams. We find that the lattice distortions can induce unconventional superconductivity hosting gapless surface Andreev bound states (SABS). Depending on the lattice distortions and superconducting pairing interactions, the unconventional inversion-odd-parity superconductivity can be either topological nodal superconductivity hosting a flat SABS or topological crystalline superconductivity hosting a gapless SABS. Remarkably, the lattice distortions increase the superconducting critical temperature, which is consistent with the experiments. Our work opens a pathway to explore and control pressure-induced topological superconductivity in doped topological semimetals.