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Li Q, Cao G, Okamoto S, Yi J, Lin W, Sales BC, Yan J, Arita R, Kuneš J, Kozhevnikov AV, Eguiluz AG, Imada M, Gai Z, Pan M, Mandrus DG. Atomically resolved spectroscopic study of Sr2IrO4: experiment and theory. Sci Rep 2013; 3:3073. [PMID: 24166292 PMCID: PMC3810661 DOI: 10.1038/srep03073] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 10/11/2013] [Indexed: 11/09/2022] Open
Abstract
Particularly in Sr2IrO4, the interplay between spin-orbit coupling, bandwidth and on-site Coulomb repulsion stabilizes a J(eff) = 1/2 spin-orbital entangled insulating state at low temperatures. Whether this insulating phase is Mott- or Slater-type, has been under intense debate. We address this issue via spatially resolved imaging and spectroscopic studies of the Sr2IrO4 surface using scanning tunneling microscopy/spectroscopy (STM/S). STS results clearly illustrate the opening of an insulating gap (150 ~ 250 meV) below the Néel temperature (TN), in qualitative agreement with our density-functional theory (DFT) calculations. More importantly, the temperature dependence of the gap is qualitatively consistent with our DFT + dynamical mean field theory (DMFT) results, both showing a continuous transition from a gapped insulating ground state to a non-gap phase as temperatures approach TN. These results indicate a significant Slater character of gap formation, thus suggesting that Sr2IrO4 is a uniquely correlated system, where Slater and Mott-Hubbard-type behaviors coexist.
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Affiliation(s)
- Qing Li
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123, China
- These authors contributed equally to this work
| | - Guixin Cao
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- These authors contributed equally to this work
| | - Satoshi Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jieyu Yi
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Wenzhi Lin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Brian C. Sales
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jiaqiang Yan
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Ryotaro Arita
- Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- JST-CREST, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Jan Kuneš
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 6, 162 53, Czech Republic
| | | | - Adolfo G. Eguiluz
- Department of Physics and Astronomy, University of Tennessee, Knoxville, 37996, USA
| | - Masatoshi Imada
- Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- JST-CREST, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Minghu Pan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - David G. Mandrus
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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