Andreev Reflection in the Fractional Quantum Hall State
Andreev Reflection in the Fractional Quantum Hall State
复制标题
DOI：
10.1103/physrevx.12.021057
复制
发表时间：
2022-06-14
影响因子：
12.5
通讯作者：
Kim, Philip
中科院分区：
文献类型：
--
作者：
Gul, Onder;Ronen, Yuval;Kim, Philip
我们构建了具有窄超导氮化铌（NbN）电极的高质量石墨烯基范德华器件，其中超导性和鲁棒分数量子霍尔（FQH）态共存。我们发现了跨越超导体分离两个FQH边的交叉安德烈夫反射（CAR）的可能特征。我们观察到的粒子状分数填充材料的CAR概率明显高于整数和孔共轭分数填充材料，并且与其他填充材料不同，CAR概率强烈依赖于温度和磁场。此外，我们在整数填充中发现了一个与填充无关的CAR概率，我们将其归因于NbN中的自旋轨道耦合，允许自旋极化边缘之间的Andreev反射。这些结果为在基于石墨烯和NbN的fqh -超导混合器件中实现新型拓扑超导相提供了一条途径。
We construct high-quality graphene-based van der Waals devices with narrow superconducting niobium nitride (NbN) electrodes, in which superconductivity and a robust fractional quantum Hall (FQH) state coexist. We find a possible signature for crossed Andreev reflection (CAR) across the superconductor separating two FQH edges. Our observed CAR probabilities in the particlelike fractional fillings are markedly higher than those in the integer and hole-conjugate fractional fillings and depend strongly on temperature and magnetic field unlike the other fillings. Further, we find a filling-independent CAR probability in integer fillings, which we attribute to spin-orbit coupling in NbN allowing for Andreev reflection between spin-polarized edges. These results provide a route to realize novel topological superconducting phases in FQH-superconductor hybrid devices based on graphene and NbN.