Nematic superconductivity stabilized by density wave fluctuations: Possible application to twisted bilayer graphene

Understand

Nematic superconductors possess unconventional superconducting order parameters that spontaneously break rotational symmetry of the underlying crystal.

• In this work we propose a mechanism for nematic superconductivity stabilized by strong density wave fluctuations in two dimensions.
• While the weak-coupling theory finds the fully gapped chiral state to be energetically stable, we show that strong density wave fluctuations result in an additional contribution to the free energy of a superconductor with multicomponent order parameters, which generally favors nematic superconductivity.
• Our theory shades light on the recent observation of rotational symmetry breaking in the superconducting state of twisted bilayer graphene.