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arXiv · 1510.07977

Quadratic Fermi Node in a 3D Strongly Correlated Semimetal

Takeshi Kondo·M. Nakayama·R. Chen·J. J. Ishikawa·E. -G. Moon·T. Yamamoto·Y. Ota·W. Malaeb·H. Kanai·Y. Nakashima·Y. Ishida·R. Yoshida·H. Yamamoto·M. Matsunami·S. Kimura·N. Inami·K. Ono·H. Kumigashira·S. Nakatsuji·L. Balents·S. Shin
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Abstract

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 Pr2Ir2O7, we identify a nontrivial 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 behavior is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semi-metal, and quantum spin and anomalous Hall states.

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Takeshi Kondo, M. Nakayama, R. Chen, J. J. Ishikawa, E. -G. Moon, T. Yamamoto, Y. Ota, W. Malaeb, H. Kanai, Y. Nakashima, Y. Ishida, R. Yoshida, H. Yamamoto, M. Matsunami, S. Kimura, N. Inami, K. Ono, H. Kumigashira, S. Nakatsuji, L. Balents, S. Shin. 2015-10-27. Quadratic Fermi Node in a 3D Strongly Correlated Semimetal. https://doi.org/10.1038/ncomms10042

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