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

Abstract

Higher-order topological superconductors (HOTSs) are topological states possessing gapless modes at the corners (hinges) of 2$d$ (3$d$) samples. While these phases of matter have recently attracted immense theoretical interest, experimental candidates remain scarce. This paper demonstrates a mechanism for HOTSs in doped topological insulators, and provides explicit modeling for a particular realization. The mechanism is effective in materials with localized orbitals. It requires a minimum doping beyond which superconductivity ensues, thus offering a useful criterion in the search for material realizations.