Slater to Mott Crossover in the Metal to Insulator Transition of Nd2⁢Ir2⁢O7

We present an angle-resolved photoemission study of the electronic structure of the three-dimensional pyrochlore iridate Nd2⁢Ir2⁢O7 through its magnetic metal-insulator transition. Our data reveal that metallic Nd2⁢Ir2⁢O7 has a quadratic band, touching the Fermi level at the Γ point, similar to that...

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Bibliographic Details
Main Author: Nakayama, M. (author)
Other Authors: Kondo, Takeshi (author), Tian, Z. (author), Ishikawa, J. J. (author), Halim, M. (author), Bareille, C. (author), Malaeb, W. (author), Kuroda, K. (author), Tomita, T. (author)
Format: article
Published: 2016
Online Access:http://hdl.handle.net/10725/16687
https://doi.org/10.1103/PhysRevLett.117.056403
http://libraries.lau.edu.lb/research/laur/terms-of-use/articles.php
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.056403
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Summary:We present an angle-resolved photoemission study of the electronic structure of the three-dimensional pyrochlore iridate Nd2⁢Ir2⁢O7 through its magnetic metal-insulator transition. Our data reveal that metallic Nd2⁢Ir2⁢O7 has a quadratic band, touching the Fermi level at the Γ point, similar to that of Pr2⁡Ir2⁢O7. The Fermi node state is, therefore, a common feature of the metallic phase of the pyrochlore iridates. Upon cooling below the transition temperature, this compound exhibits a gap opening with an energy shift of quasiparticle peaks like a band gap insulator. The quasiparticle peaks are strongly suppressed, however, with further decrease of temperature, and eventually vanish at the lowest temperature, leaving a nondispersive flat band lacking long-lived electrons. We thereby identify a remarkable crossover from Slater to Mott insulators with decreasing temperature. These observations explain the puzzling absence of Weyl points in this material, despite its proximity to the zero temperature metal-insulator transition.