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Probing entropy and magnetization in graphene heterostructures

ORAL

Abstract

We developed a technique to determine entropy and magnetization by measuring chemical potential in van der Waals heterostructures. In twisted bilayer graphene with near 1.1 degree rotate angle, large entropy – on the order of unity per unit cell in unit of Boltzmann constant – is discovered around filling factor +-1. The entropy is suppressed by in-plane magnetic field, suggesting a weakly coupled isospin-ordered phase with strong fluctuations at higher temperatures, while the corresponding low temperature ground state is isospin unpolarized. This is in contrast with the typical scenario that ordered phase are favored at lower temperature, and is an analogue to the Pomerachuk effect discovered in 3He. We also applied this technique to  non-Moiré type graphene systems, such as Bernal stack bilayer graphene.

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Presenters

  • Fangyuan Yang

    University of California, Santa Barbara

Authors

  • Fangyuan Yang

    University of California, Santa Barbara

  • Yu Saito

    University of California, Santa Barbara

  • Jingyuan Ge

    University of California, Santa Barbara

  • Xiaoxue Liu

    Brown University

  • Takashi Taniguchi

    National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science, NIMS, Kyoto Univ, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Ibaraki 305-0044, Japan., 3 National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science; 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Materials Science, Tsukuba, Japan, National Institute of Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, National Institute for Materials Science (Japan), International Center for Materials Nanoarchitectonics, National Institute for Materials Science, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Kyoto University, International Center for Materials Nanoarchitectonics, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Japan, International Center for Materials Nanoarchitectonics, National Institute for MaterialsScience, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, Japan, National Institute for Material Science, National Institute of Material Sciences, Japan, NIMS, Tsukuba, 2National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan., National Institute of Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science, Japan, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan., NIMS, Japan, National Institute for Materials Science (NIMS), NIMS. Japan, International Center for Material Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan, International Center for Material Nanoarchitectonics, National Institute for Materials Science, National Institute for Materials Science Tsukuba, National Institute for Materials Science, 1-1 Namiki, National Institute for Materials Science of Japan, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, NIMS - National Institute for Material Science, Japan, International Center for Materials Nanoarchitectonics, National Institute for Material Science, Tsukuba, Ibaraki 305-0044, Japan., National Institute for Material Science, Tsukuba, National Institute for Materials Science, International Center for Materials Nanoarchitectonics, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Material Science, National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan

  • Kenji Watanabe

    National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science, NIMS, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan., Research Center for Functional Materials, National Institute for Materials Science, Advanced, Materials Laboratory, NIMS, 3 National Institute for Materials Science, Tsukuba, Japan, National Institute for Materials Science; 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Materials Science, Tsukuba, Japan, National Institute of Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, National Institute for Materials Science (Japan), National Institute for Materials Science, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan, Research Center for Functional Materials, National Institute for Materials Science, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, Japan, National Institute for Material Science, National Institute of Material Sciences, Japan, NIMS, Tsukuba, 2National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan., National Institute of Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science Japan, NIMS, Japan, nims, National Institute for Materials Science, Research Center for Functional Materials, Japan, National Institute for Materials Science Tsukuba, National Institute for Materials Science, 1-1 Namiki, National Institute for Materials Science of Japan, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, NIMS - National Institute for Material Science, Japan, Research Center for Functional Materials, National Institute for Material Science, Tsukuba, Ibaraki, 305-0044, Japan., National Institute for Material Science, Tsukuba, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, National Institute for Materials Science (NIMS), National Institute for Materials Science, Research Center for Functional Materials, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, National Institute of Material Science, Kyoto Univ, National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan

  • Jia Li

    Brown University

  • Erez Berg

    Weizmann Institute of Science

  • Andrea Young

    University of California, Santa Barbara