Atomically resolved spectroscopic study of Sr2IrO4: Experiment and theory

Particularly in Sr 2 IrO 4 , 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...

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Bibliographic Details
Published in:Scientific reports 2013-10, Vol.3 (1), p.3073-3073, Article 3073
Main Authors: Li, Qing, Cao, Guixin, Okamoto, Satoshi, Yi, Jieyu, Lin, Wenzhi, Sales, Brian C., Yan, Jiaqiang, Arita, Ryotaro, Kuneš, Jan, Kozhevnikov, Anton V., Eguiluz, Adolfo G., Imada, Masatoshi, Gai, Zheng, Pan, Minghu, Mandrus, David G.
Format: Article
Language:English
Subjects:
639/301/1034/1038
639/301/119/2795
639/766/119/544
639/766/119/995
Critical phenomena
Humanities and Social Sciences
Laboratories
Low temperature
Microscopy
multidisciplinary
Phase transitions
Physics
Scanning tunneling microscopy
Science
Science (multidisciplinary)
Short term memory
Spectroscopy
Spectrum analysis
Temperature effects
Topography
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Summary:Particularly in Sr 2 IrO 4 , 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 Sr 2 IrO 4 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 (T N ), 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 T N . These results indicate a significant Slater character of gap formation, thus suggesting that Sr 2 IrO 4 is a uniquely correlated system, where Slater and Mott-Hubbard-type behaviors coexist.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep03073