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Observation of the two-gap spectrum in superconducting magic-angle twisted trilayer graphene

ORAL

Abstract

Magic-angle twisted multilayer graphene has emerged as a moiré material family with strong electronic correlations and robust superconductivity. However, the origin of superconducting pairing in this system is still elusive. We study magic-angle twisted trilayer graphene (MATTG) utilizing scanning tunneling microscopy (STM) and spectroscopy, focusing on highly twist-angle homogenous regions. In addition to Andreev reflection signatures and the previously observed tunneling gap, we surprisingly resolved an additional inner gap pinned to the Fermi energy in a narrow range of filling factors. The two gaps show distinct magnetic field and temperature dependence, with the inner gap following the behavior in line with reported transport measurements, disappearing at Tc = 2K and Bc = 300mT, while the outer gap persists until much higher temperatures and fields. Measurements on the MATTG domain wall further reveal the distinct behavior of the two gaps. We will also discuss the possible explanation of the two gaps derived from peculiar correlation-driven phenomena in twisted multilayer graphene systems.

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Presenters

  • Hyunjin Kim

    Caltech

Authors

  • Hyunjin Kim

    Caltech

  • Youngjoon Choi

    University of California, Santa Barbara

  • Etienne Lantagne-Hurtubise

    Caltech

  • Cyprian K Lewandowski

    National High Magnetic Field Laboratory, Florida State University

  • Alex Thomson

    University of California, Davis

  • Lingyuan Kong

    Caltech

  • Haoxin Zhou

    University of California, Berkeley and Lawrence Berkeley National Laboratory, University of California, Berkeley

  • Eli Nathaniel Baum

    Caltech

  • Yiran Zhang

    Harvard University, Caltech

  • Ludwig Holleis

    University of California Santa Barbara, University of California, Santa Barbara

  • Kenji Watanabe

    National Institute for Materials Science, NIMS, Research Center for Functional Materials, National Institute for Materials Science, Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, National Institute of Material Science, Tsukuba, Japan, National Institute of Materials Science, Advanced Materials Laboratory, National Institute for Materials Science

  • Takashi Taniguchi

    National Institute for Materials Science, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, International Center for Materials Nanoarchitectonics, National Institute of Material Science, Tsukuba, Japan, Advanced Materials Laboratory, National Institute for Materials Science

  • Andrea F Young

    University of California, Santa Barbara, University of California Santa Barbara, University of California at Santa Barbara

  • Jason F Alicea

    Caltech

  • Stevan Nadj-Perge

    Caltech