Valley-Dependent Crossed Andreev Reflection in Graphene/Superconductor/Line-Defect Superlattice Junctions

Graphene, a two-dimensional material with remarkable electronic properties, offers significant potential for valley-based electronic devices. In this study, we explore a novel mechanism to achieve valley-dependent, near-perfect crossed Andreev reflection (CAR) in graphene-based junctions by utilizing the valley degree of freedom in a graphene/superconductor/line defect superlattice (LDGSL) structure. The LDGSL introduces unique valley-filtering effects. By incorporating staggered pseudospin potentials and intrinsic spin-orbit coupling in the left graphene electrode, the system selectively enhances CAR for electrons in the K \('\) $_{}^{\prime }$ valley, while simultaneously suppressing local Andreev reflection and elastic cotunneling (ECT). Numerical simulations reveal that CAR is nearly perfect for K \('\) $_{}^{\prime }$ valley electrons with spin-up, while for K valley electrons with spin-down, only ECT is observed. Our results demonstrate the viability of this approach for valley-polarized CAR in graphene/ superconductor junctions, providing a pathway for the development of valley-based quantum information devices.