Optoelectronically controlled Andreev reflection in graphene based antiferromagnetic superconducting heterojunctions

Abstract We systematically investigated electrically modulated Andreev reflection in graphene-based antiferromagnetic-superconducting (AF/S) single junctions and crossed Andreev reflection in antiferromagnetic-superconducting-antiferromagnetic (AF/S/AF) double junctions. In single-junction systems, the synergistic effect of the electric field and antiferromagnetic exchange field lifts spin degeneracy, while the combined action of the electric field and nonresonant circularly polarized light breaks the valley degeneracy. This mechanism enables the realization of spin-valley filtering-related Andreev reflection in graphene-based antiferromagnetic-superconducting heterojunctions. For the double-junction system, a valley-spin switching effect between pure elastic co-tunneling and pure crossed Andreev reflection is achieved when the electric field is tuned from negative to positive. Additionally, we found that the antiferromagnetic field and light field influence the central positions of elastic co-tunneling and crossed Andreev reflection, while the energy ranges of these processes are modulated by the incident energy and Fermi energy. The results of this study show that the device can achieve pure crossed Andreev reflection and spin-valley filtering under electric field modulation, providing a new platform for the application of spin-valley electronics in superconducting quantum systems.