Enhanced superconductivity through virtual tunneling in Bernal bilayer graphene coupled to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>WSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>
Yang-Zhi Chou, Fengcheng Wu, S. Das Sarma
Abstract
Motivated by a recent experiment (Y. Zhang et al., arXiv:2205.05087), we investigate a possible mechanism that enhances superconductivity in hole-doped Bernal bilayer graphene due to a proximate ${\mathrm{WSe}}_{2}$ monolayer. We show that the virtual tunneling between ${\mathrm{WSe}}_{2}$ and Bernal bilayer graphene, which is known to induce Ising spin-orbit coupling, can generate an additional attraction between two holes, providing a potential explanation for enhancing superconductivity in Bernal bilayer graphene. Using microscopic interlayer tunneling, we derive the Ising spin-orbit coupling and the effective attraction as functions of the twist angle between Bernal bilayer graphene and the ${\mathrm{WSe}}_{2}$ monolayer. Our theory provides an intuitive and physical explanation for the intertwined relation between Ising spin-orbit coupling and superconductivity enhancement, which should motivate future studies.