Specular interband Andreev reflections at van der Waals interfaces between graphene and NbSe 2

D. K. Efetov, L. Wang, C. Handschin, K. B. Efetov, J. Shuang, R. Cava, T. Taniguchi, K. Watanabe, J. Hone, C. R. Dean, P. Kim

Research output: Contribution to journalArticlepeer-review

153 Scopus citations


Electrons incident from a normal metal onto a superconductor are reflected back as holes - a process called Andreev reflection. In a normal metal where the Fermi energy is much larger than a typical superconducting gap, the reflected hole retraces the path taken by the incident electron. In graphene with low disorder, however, the Fermi energy can be tuned to be smaller than the superconducting gap. In this unusual limit, the holes are expected to be reflected specularly at the superconductor-graphene interface owing to the onset of interband Andreev processes, where the effective mass of the reflected holes changes sign. Here we present measurements of gate-modulated Andreev reflections across the low-disorder van der Waals interface formed between graphene and the superconducting NbSe 2. We find that the conductance across the graphene-superconductor interface exhibits a characteristic suppression when the Fermi energy is tuned to values smaller than the superconducting gap, a hallmark for the transition between intraband retro Andreev reflections and interband specular Andreev reflections.

Original languageEnglish (US)
Pages (from-to)328-332
Number of pages5
JournalNature Physics
Issue number4
StatePublished - Apr 1 2016

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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