Weak-Pairing Higher Order Topological Superconductors

Understand

Conventional topological superconductors are fully gapped in the bulk but host gapless Majorana modes on their boundaries.

• We instead focus on a new class of superconductors, second-order topological superconductors, that have gapped, topological surfaces and gapless Majorana modes instead on lower-dimensional boundaries, i.e., corners of a two-dimensional system or hinges for a three-dimensional system.
• Here we propose two general scenarios in which second-order topological superconductivity can be realized spontaneously with weak-pairing instabilities.
• First, we show that $p_x+ip_y$-wave pairing in a (doped) Dirac semimetal in two dimensions with four mirror symmetric Dirac nodes realizes second-order topological superconductivity.