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

Abstract

Recent experimental findings have demonstrated the occurrence of superconductivity in Bernal bilayer graphene when 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 the 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.