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.

*This work has been primarily supported by the Office of Naval Research (grant no. N142112635) and in part by the Institute for Quantum Information and Matter, an National Science Foundation Physics Frontiers Center (PHY-2317110). H.K. acknowledges support from the Kwanjeong fellowship.

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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