Light-modulated Andreev effects in graphene-based superconducting junctions

作     者：Miao Yu Deliang Cao Hong Wang Yafang Xu Fenghua Qi Xingfei Zhou Guojun Jin 

作者机构：New Energy Technology Engineering Laboratory of Jiangsu Province School of Science College of Physics Science and Technology School of Electronic Engineering School of Physics Science and Technology National Laboratory of Solid State Microstructures Department of Physics and Collaborative Innovation Center of Advanced Microstructures 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2024年第110卷第15期

页      面：155420页

核心收录：

基　　金：Natural Science Foundation of Nanjing University of Posts and Telecommunications, (202211460004Z, 202311460036Z, NY222163, NY223107) National Natural Science Foundation of China, NSFC, (12104232, 12074156, 11804167, 11804291) 

主　　题：Andreev bound states Andreev reflection Josephson effect Graphene Superconducting devices Band structure methods Bogoliubov-de Gennes equations Tight-binding model 

摘      要：We investigate the transport properties, including Andreev reflection, 0−π transition, and crossed Andreev reflection, of graphene-based superconducting junctions modulated by an off-resonant circularly polarized light and a staggered sublattice potential. Using the Dirac-Bogoliubov–de Gennes equation and the Blonder-Tinkham-Klapwijk formula associated with numerical calculations, we can make the following findings. In a graphene-based normal conductor/superconductor (NS) junction, the differential conductance from Andreev reflection can be used to distinguish band structures. However, in a graphene-based superconductor/normal conductor/superconductor (SNS) junction, the valley polarization is induced and brings in a 0−π transition. Moreover, in a graphene-based normal conductor/superconductor/normal conductor (NSN) junction, the opposite valley polarization in two normal regions can lead to the pure and even perfect crossed Andreev reflections. The appreciable differential conductance of the pure crossed Andreev reflection is found for the 20–50 nm junction length, far less than the previous result in the graphene-based NSN junction, and it is helpful for the integration of superconducting quantum circuits. Our findings provide experimental possibilities to characterize the band structures, to realize the valley polarization-induced 0−π transition, and to design the valley-based highly efficient Cooper pair splitter in the light-modulated graphene-based superconducting junctions.