Spontaneous Vortex-Antivortex Lattice and Majorana Fermions in Rhombohedral Graphene

The discovery of superconducting states in multilayer rhombohedral graphene with spin and valley polarization [1] has raised an interesting question: how does superconductivity cope with time-reversal symmetry breaking? In this Letter, using Ginzburg-Landau theory and microscopic calculation, we predict the existence of a new superconducting state at low electron density, which exhibits a spontaneously formed lattice of vortices and antivortices hosting Majorana zero modes in their cores. We further identify this vortex-antivortex lattice state in the experimental phase diagram and describe its experimental manifestations.