Anomalous periodicity of magnetic interference patterns in encapsulated graphene Josephson junctions
Anomalous periodicity of magnetic interference patterns in encapsulated graphene Josephson junctions
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DOI：
10.1103/physrevresearch.1.033084
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发表时间：
2019-11-07
影响因子：
4.2
通讯作者：
Finkelstein, G.
中科院分区：
文献类型：
--
作者：
Ke, C. T.;Draelos, A. W.;Finkelstein, G.
我们研究了弹道石墨烯约瑟夫森结中测量的作为磁场函数的超流干涉图样。在高掺杂时，观察到预期的Phi(0)周期“夫琅和费”图案，表明电流分布均匀。在狄拉克点附近，我们发现了接近2Phi(0)周期的反常干扰，类似于预测的带有e而不是2e电荷的拓扑Andreev束缚态。随着温度的升高，这一特征持续存在，排除了非正弦电流-相位关系。它也持续存在于尖锐真空边缘被消除的结合处。我们的结果表明，所观察到的行为可能源于弹道石墨烯约瑟夫森结的一种本征性质，尽管确切的机制尚不清楚。
We investigate supercurrent interference patterns measured as a function of magnetic field in ballistic graphene Josephson junctions. At high doping, the expected Phi(0)-periodic "Fraunhofer" pattern is observed, indicating a uniform current distribution. Close to the Dirac point, we find anomalous interferences that are close to a 2 Phi(0) periodicity, similar to that predicted for topological Andreev bound states carrying a charge of e instead of 2e. This feature persists with increasing temperature, ruling out a nonsinusoidal current-phase relationship. It also persists in junctions in which sharp vacuum edges are eliminated. Our results indicate that the observed behavior may originate from an intrinsic property of ballistic graphene Josephson junctions, though the exact mechanism remains unclear.