Observation of flat bands and Dirac cones in a pyrochlore lattice superconductor
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 demonstrate that an interwoven kagome network—a pyrochlore lattice—can host a three dimensional (3D) localization of electron wavefunctions. Meanwhile, the nonsymmorphic symmetry of the pyrochlore lattice guarantees all band crossings at the Brillouin zone X point to be 3D gapless Dirac points, which was predicted theoretically but never yet observed experimentally. Through a combination of angle-resolved photoemission spectroscopy, fundamental lattice model and density functional theory calculations, we investigate the novel electronic structure of a Laves phase superconductor with a pyrochlore sublattice, CeRu2. We observe evidence of flat bands originating from the Ce 4f orbitals as well as flat bands from the 3D destructive interference of the Ru 4d orbitals. We further observe the nonsymmorphic symmetry-protected 3D gapless Dirac cone at the X point. Our work establishes the pyrochlore structure as a promising lattice platform to realize and tune novel emergent phases intertwining topology and many-body interactions.
Authors
- Hongxiong Liu (ORCID: https://orcid.org/0000-0001-6769-6821)
- Ji Seop Oh (ORCID: https://orcid.org/0000-0002-6894-3983)
- Pengcheng Dai (ORCID: https://orcid.org/0000-0002-6088-3170)
- Jia‐Xin Yin (ORCID: https://orcid.org/0000-0003-2661-4206)
- Ziqin Yue (ORCID: https://orcid.org/0000-0003-3212-7113)
- Liangzi Deng (ORCID: https://orcid.org/0000-0002-5379-2772)
- Chandan Setty (ORCID: https://orcid.org/0000-0003-4829-1508)
- Sen Shao (ORCID: https://orcid.org/0000-0001-5530-2493)
- Dong-Hui Lu (ORCID: https://orcid.org/0000-0002-9708-0443)
- C. W. Chu (ORCID: https://orcid.org/0000-0003-3955-7095)
- R. J. Birgeneau
- Qimiao Si A (ORCID: https://orcid.org/0000-0003-1357-2705)
- Jonathan D. Denlinger (ORCID: https://orcid.org/0000-0001-7645-1631)
- Yucheng Guo (ORCID: https://orcid.org/0000-0003-0372-1578)
- Yuan Ping Feng (ORCID: https://orcid.org/0000-0003-2190-2284)
- Guoqing Chang (ORCID: https://orcid.org/0000-0003-1180-3127)
- Jing‐Yang You (ORCID: https://orcid.org/0000-0003-4559-6592)
- M. Zahid Hasan (ORCID: https://orcid.org/0000-0001-9730-3128)
- Jianwei Huang (ORCID: https://orcid.org/0000-0002-5433-1513)
- Makoto Hashimoto (ORCID: https://orcid.org/0000-0003-1689-8997)
- Ming Yi (ORCID: https://orcid.org/0000-0001-8934-7905)
- Sergey Gorovikov
- Yichen Zhang (ORCID: https://orcid.org/0000-0001-6792-330X)
- Youguo Shi
- J. W. Allen (ORCID: https://orcid.org/0000-0001-7378-019X)
Institutions
- Lawrence Berkeley National Laboratory (US)
- National University of Singapore (SG)
- Nanyang Technological University (SG)
- Chinese Academy of Sciences (CN)
- Princeton University (US)
- University of Michigan (US)
- SLAC National Accelerator Laboratory (US)
- Stanford Synchrotron Radiation Lightsource (US)
- Institute of Physics (CN)
- National Laboratory for Superconductivity (CN)
- University of Houston (US)
- Rice University (US)
- Canadian Light Source (Canada) (CA)
- University of California, Berkeley (US)
Publication Details
- Journal
- npj Quantum Materials
- Published
- 2024-09-19
- DOI
- https://doi.org/10.1038/s41535-024-00683-x
- Citations
- 18
- Primary Topic
- Advanced Condensed Matter Physics
- Type
- article
- Field-Weighted Citation Impact
- 5.60
Funders
- U.S. Department of Energy
- Gordon and Betty Moore Foundation
- University of Houston
- Rice University
- T.L.L Temple Foundation
- John J. and Rebecca Moores Endowment
- National Research Foundation
- National Research Foundation Singapore
- Ministry of Education - Singapore
- Nanyang Technological University
- National Natural Science Foundation of China
- Chinese Academy of Sciences
- Ministry of Education, India
- Office of Science
- U.S. Air Force
- Texas Center for Superconductivity, University of Houston
- Office of Naval Research
- Basic Energy Sciences
- Air Force Office of Scientific Research
- SLAC National Accelerator Laboratory