Observation of Three-Dimensional Flat Bands and Dirac Cones in a Pyrochlore Superconductor

ORAL

Abstract

Emergent phases often appear when the electronic kinetic energy is comparable to the Coulomb interactions. One approach to seek material systems as hosts of such emergent phases is to realize localization of electronic wavefunctions due to the geometric frustration inherent in the crystal structure, resulting in flat electronic bands. Recently, such efforts have found a wide range of exotic phases in the two-dimensional kagome lattice, including magnetic order, time-reversal symmetry breaking charge order, nematicity, and superconductivity. However, the interlayer coupling of the kagome layers disrupts the destructive interference needed to completely quench the kinetic energy. Here we experimentally demonstrate that an interwoven kagome network—a pyrochlore lattice—can host a three-dimensional localization of electron wavefunctions. In particular, through a combination of angle-resolved photoemission spectroscopy, fundamental lattice model and density functional theory calculations, we present the novel electronic structure of a pyrochlore superconductor, CeRu2. We find striking flat bands along all momentum directions. We further find three-dimensional gapless Dirac cones predicted originally by theory in the diamond lattice space group with nonsymmorphic symmetry. Our work establishes the pyrochlore structure as a promising lattice platform to realize and tune novel emergent phases intertwining topology and many-body interactions.

*U.S. Department Of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Gordon and Betty Moore Foundation's EPiQS Initiative through grant No. GBMF9470 and the Robert A. Welch Foundation Grant No. C-2024.

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Presenters

  • Jianwei Huang

    • Rice University

Authors

  • Jianwei Huang

    • Rice University

  • Chandan Setty

    • Rice University

  • Liangzi Deng

    • University of Houston
    • Department of Physics and Texas Center for Superconductivity, University of Houston

  • Jingyang You

    • National University of Singapore

  • Hongxiong Liu

    • Institute of Physics, Chinese Academy of Sciences
    • Institute of Physics, Chinese Academy of Sciences, Beijing, China
    • Chinese Academy of Sciences

  • Sen Shao

    • Nanyang Technological University

  • Ji Seop Oh

    • University of California Berkeley

  • Yucheng Guo

    • Rice University

  • Yichen Zhang

    • Rice University

  • Ziqin Yue

    • Rice University

  • Jia-Xin Yin

    • 2Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
    • Princeton University

  • Makoto Hashimoto

    • SLAC - Natl Accelerator Lab

  • Donghui Lu

    • SLAC - Natl Accelerator Lab

  • Sergey Gorovikov

    • Canadian Light Source
    • Canadian Lightsource

  • Pengcheng Dai

    • Rice University

  • M. Zahid M Hasan

    • Princeton University

  • Yuan P Feng

    • National University of Singapore
    • Natl Univ of Singapore

  • Robert J Birgeneau

    • University of California, Berkeley

  • Youguo Shi

    • Beijing National Laboratory for Condensed Matter Physics
    • Institute of Physics, Chinese Academy of Sciences
    • Institute of Physics, Chinese Academy of Sciences, Beijing, China
    • Chinese Academy of Sciences

  • Ching-Wu W Chu

    • University of Houston
    • Department of Physics and Texas Center for Superconductivity, University of Houston

  • Guoqing Chang

    • Nanyang Technological University
    • Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore
    • Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore

  • Qimiao Si

    • Rice University

  • Ming Yi

    • Rice University