Ren Chongdan, Sun Minglei, Tian Hongyu, Wang Sake
Département de physique, Université normale de Zunyi, Kweichow, 563002, China.
Department of Physics, NANOlab Center of Excellence, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium.
Sci Rep. 2025 May 7;15(1):15917. doi: 10.1038/s41598-025-01019-w.
We study the crossed Andreev reflection and the nonlocal transport in the staggered graphene/superconductor/periodic line defect superlattice (LDGSL) junctions. The staggered pseudospin potential in the left graphene electrode suppress the local Andreev reflection, while the elastic cotunneling of K' valley electrons is inhibited due to the exclusive rightward motion of K valley electrons in the right LDGSL electrode, thereby enabling the realization of dominant intravalley crossed Andreev reflection for incident electrons from the K' valley. Meanwhile, the intravalley elastic cotunneling occurs while both local Andreev reflection and crossed Andreev reflection are completely eliminated for incident electrons in the K valley. Furthermore, the probability of intervalley crossed Andreev reflection scattering is significantly lower than that of intravalley CAR scattering across a broad range of incident angles and electron energies. Our results are helpful for designing the flexible and high-efficiency Cooper pair splitter based on the valley degree of freedom.
我们研究了交错石墨烯/超导体/周期性线缺陷超晶格（LDGSL）结中的交叉安德烈夫反射和非局域输运。左石墨烯电极中的交错赝自旋势抑制了局部安德烈夫反射，而由于右LDGSL电极中K谷电子仅向右运动，K'谷电子的弹性共隧穿受到抑制，从而使得对于来自K'谷的入射电子能够实现占主导地位的谷内交叉安德烈夫反射。同时，对于K谷中的入射电子，在局部安德烈夫反射和交叉安德烈夫反射都完全消除时会发生谷内弹性共隧穿。此外，在很宽的入射角和电子能量范围内，谷间交叉安德烈夫反射散射的概率显著低于谷内交叉安德烈夫反射（CAR）散射的概率。我们的结果有助于基于谷自由度设计灵活高效的库珀对分裂器。
