Spin polarized pairing induced by the magnetic field in the Bernal bilayer graphene

Abstract

Abstract Recent experimental findings have demonstrated the occurrence of superconductivity in Bernal bilayer graphene, induced by a magnetic field. In this study, we conduct a theoretical investigation of the potential pairing symmetry within this superconducting system. By developing a theoretical model, we primarily calculate the free energy of the system with $p+ip$-wave parallel spin pairing, $p+ip$-wave anti-parallel spin pairing, and $d+id$-wave pairing symmetry. Our results confirm that the magnetic field is indeed essential for generating superconductivity. We discover that the $p+ip$-wave parallel spin pairing leads to a lower free energy for the system. The numerical calculations of the energy band structure, zero-energy spectral function, and density of states for each of the three pairing symmetries under consideration show a strong consistency with the free energy results.