Valley-based Cooper pair splitting via topologically confined channels in bilayer graphene
Valley-based Cooper pair splitting via topologically confined channels in bilayer graphene
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DOI：
10.1103/physrevb.92.241404
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发表时间：
2015-09
影响因子：
3.7
通讯作者：
A. Schroer;P. Silvestrov;P. Recher
中科院分区：
文献类型：
--
作者：
A. Schroer;P. Silvestrov;P. Recher
双层石墨烯在不同层间势或堆叠顺序的区域之间的畴壁处具有谷手征一维模式。当这样的通道靠近超导体时，穿隧进入其中的库珀对中的两个电子以相反的方向移动，因为它们属于由时间反演对称性相关的不同谷。这是库珀对分裂的一个动力学变体，它既不需要库仑排斥也不需要能量过滤，而是在没有原子尺度缺陷的情况下通过谷同位旋的鲁棒性来实施。我们推导出一个有效的模型的导模附近的s-波超导体，计算的电导进行分裂和自旋纠缠电子对，并解释它作为本地Andreev反射过程的结果，而交叉Andreev反射是不存在的。
Bilayer graphene hosts valley-chiral one dimensional modes at domain walls between regions of different interlayer potential or stacking order. When such a channel is brought into proximity to a superconductor, the two electrons of a Cooper pair which tunnel into it move in opposite directions because they belong to different valleys related by the time-reversal symmetry. This is a kinetic variant of Cooper pair splitting, which requires neither Coulomb repulsion nor energy filtering but is enforced by the robustness of the valley isospin in the absence of atomic-scale defects. We derive an effective model for the guided modes in proximity to an s-wave superconductor, calculate the conductance carried by split and spin-entangled electron pairs, and interpret it as a result of local Andreev reflection processes, whereas crossed Andreev reflection is absent.