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Title: Quadratic Fermi node in a 3D strongly correlated semimetal

We report that strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr 2Ir 2O 7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Lastly, our discovery implies that Pr 2Ir 2O 7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.
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  1. Univ. of Tokyo (Japan)
  2. Univ. of California, Santa Barbara, CA (United States); Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Santa Barbara, CA (United States); Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea)
  4. Univ. of Tokyo (Japan); Beirut Arab Univ., Beirut (Lebanon)
  5. Institute for Molecular Science, Okazaki (Japan); Toyota Technological Institute, Nagoya (Japan)
  6. Institute for Molecular Science, Okazaki (Japan); Osaka Univ. (Japan)
  7. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba (Japan)
  8. Univ. of Tokyo (Japan); Japan Science and Technology Agency (JST), Saitama (Japan). PRESTO
  9. Kavli Institute for Theoretical Physics, Santa Barbara, CA (United States)
Publication Date:
Grant/Contract Number:
FG02-08ER46524; DMR 1121053
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
Country of Publication:
United States
OSTI Identifier: