title: Atomically resolved spectroscopic study of Sr2IrO4: experiment and theory.
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.
authors.affiliation: 1] Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA [2] Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123, China [3].
authors.forename: Qing
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authors.lastname: Li
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authors.lastname: Okamoto
authors.forename: Jieyu
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authors.forename: Wenzhi
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authors.lastname: Lin
authors.forename: Brian C
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authors.forename: Jiaqiang
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authors.lastname: Yan
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authors.lastname: Eguiluz
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authors.lastname: Imada
authors.forename: Zheng
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authors.lastname: Gai
authors.forename: Minghu
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authors.lastname: Pan
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authors.lastname: Mandrus