Majorana flat bands create competing superconducting states

Researchers at Uppsala University have discovered that a standard uniform superconducting state is impossible at zero temperature when Majorana flat bands are present. Their self-consistent calculations reveal two competing superconducting phases, a “pair density wave” with amplitude modulations and a “phase crystal” with phase modulations, both localized to the edges of the topological superconductor. These phases emerge because they lower the system’s free energy by gapping out the Majorana flat band, a process primarily controlled by the chemical potential, and establish the ubiquity of emergent nonuniform superconducting phases in these materials. The team’s self-consistent calculations further demonstrate the existence of a second competing phase, a “phase crystal,” distinguished by edge-localized phase modulations in the superconducting order parameter. Unlike the pair density wave, which exhibits amplitude modulations at the…