论文部分内容阅读
We theoretically study the differential conductance of a graphene/graphene superconductor junction, where the valley polarization of Dirac electrons is considered in the nonsuperconducting region. It is shown that the subgap conductance will increase monotonically with the valley-polarization strength when the chemical potential μ is near the Dirac point μ≤ 3?(? is the superconducting gap), whereas it will decrease monotonically when μ is far away from the Dirac point, μ≥ 5?.The former case is induced by the specular Andreev reflection while the retro-reflection accounts for the later result. Our findings may shed light on the control of conductance of a graphene superconductor junction by valley polarization.
We theoretically study the differential conductance of a graphene / graphene superconductor junction, where the valley polarization of dirac electrons is added in the non-superconducting region. It shows that the subgap conductance will monotonically increase with the valley-polarization strength when the chemical potential μ is near the Dirac point μ ≤ 3? (? is the superconducting gap), but it will decrease monotonically when μ is far away from the Dirac point, μ ≥ 5 ?, the former case is induced by the specular Andreev reflection while the retro- reflection accounts for the later result. Our findings may shed light on the control of conductance of a graphene superconductor junction by valley polarization.