Intrinsic first and higher-order topological superconductivity in a doped topological insulator

Abstract

We explore higher order topological superconductivity in an artificial Dirac material with intrinsic spin-orbit coupling, which is a doped Z2 topological insulator in the normal state. A mechanism for superconductivity due to repulsive interactions -pseudospin pairing -has recently been shown to naturally result in higher-order topology in Dirac systems past a minimum chemical potential [1].Here we apply this theory through microscopic modeling of a superlattice potential imposed on an inversion symmetric hole-doped semiconductor heterostructure, known as hole-based semiconductor artificial graphene, and extend previous work to include the effects of spin-orbit coupling. We find that spin-orbit coupling enhances interaction effects, providing an experimental handle to increase the efficiency of the superconducting mechanism. We show that the phase diagram of these systems, as a function of chemical potential and interaction strength, contains three superconducting states -a first-order topological p + ip state, a second-order topological spatially modulated p + iτ p state, and a second-order topological extended s-wave state, sτ . We calculate the symmetry-based indicators for the p+iτ p and sτ states, which prove these states possess second-order topology. Exact diagonalisation results are presented which illustrate the interplay between the boundary physics and spin orbit interaction. We argue that this class of systems offer an experimental platform to engineer and explore first and higher-order topological superconducting states.

Higher-order topological superconductivity from repulsive interactions in kagome and honeycomb systems

“…Unlike the p-wave states, the s-wave state is protected against the effects of weak disorder by a generalized Anderson's theorem, so this state might posses a higher T c than the topological phases in a sufficiently disordered system. In a separate study, we also suggest that these two phases may arise due to spin-orbit coupling and study their properties in detail [71].…”

“…This phase possesses a Chern number which leads to a gapless, anomalous edge spectrum. In a separate study, we show that this phase may become dominant when spin orbit coupling is present, and analyze the topology of this phase in detail [71].…”

Chiral excitonic order from twofold van Hove singularities in kagome metals

“…First principles calculations could relate our phase diagram to these experiments by determining δ, µ and couplings as a function of pressure. Variation of doping and pressure indicates the presence of two distinct superconducting phases [46][47][48]; it is possible that the TvHS dominates the physics in one doping regime, while other interaction physics could be important elsewhere in the phase diagram [82][83][84][85][86][87]-e.g. it has been shown that sublattice interference near the K-points can result in higher-order topological multigap s-or p-wave states [11,86,87].…”

Topological Phases of an Interacting Majorana Benalcazar–Bernevig–Hughes Model

“…The question was addressed by considering the effect of Coulomb repulsive interactions [19][20][21] and/or by developing a number-conserving theory [22] in order to go beyond the BCS approximation. In particular, some recent studies investigated the physical properties of HOTSCs when Coulomb interactions are taken into account [23,24].…”