• 文献标题:   Andreev Reflections in NbN/Graphene Junctions under Large Magnetic Fields
  • 文献类型:   Article
  • 作  者:   WANG D, TELFORD EJ, BENYAMINI A, JESUDASAN J, RAYCHAUDHURI P, WATANABE K, TANIGUCHI T, HONE J, DEAN CR, PASUPATHY AN
  • 作者关键词:   twodimensional, van der waal, graphene, niobium nitride, superconductivity, andreev reflection, quantum hall effect, zeeman splitting
  • 出版物名称:   NANO LETTERS
  • ISSN:   1530-6984 EI 1530-6992
  • 通讯作者地址:  
  • 被引频次:   1
  • DOI:   10.1021/acs.nanolett.1c02020 EA SEP 2021
  • 出版年:   2021

▎ 摘  要

Hybrid superconductor/graphene (SC/g) junctions are excellent candidates for investigating correlations between Cooper pairs and quantum Hall (QH) edge modes. Experimental studies are challenging as Andreev reflections are extremely sensitive to junction disorder, and high magnetic fields are required to form QH edge states. We fabricated low-resistance SC/g interfaces, composed of graphene edge contacted with NbN with a barrier strength of Z approximate to 0.4, that remain superconducting under magnetic fields larger than 18 T. We establish the role of graphene's Dirac band structure on zero-field Andreev reflections and demonstrate dynamic tunability of the Andreev reflection spectrum by moving the boundary between specular and retro Andreev reflections with parallel magnetic fields. Through the application of perpendicular magnetic fields, we observe an oscillatory suppression of the 2-probe conductance in the nu = 4 Landau level attributed to the reduced efficiency of Andreev processes at the NbN/g interface, consistent with theoretical predictions.