Andreev Reflection in the Fractional Quantum Hall State

Önder Gül, Yuval Ronen, Si Young Lee, Hassan Shapourian, Jonathan Zauberman, Young Hee Lee, Kenji Watanabe, Takashi Taniguchi, Ashvin Vishwanath, Amir Yacoby, Philip Kim

Research output: Contribution to journalArticlepeer-review

Abstract

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.
Original languageEnglish
Article number21057
JournalPhysical Review X
Volume12
Issue number2
DOIs
StatePublished - Jun 2022
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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