Atomically resolved spectroscopic study of Sr2 IrO 4: Experiment and theory

Qing Li, Guixin Cao, Satoshi Okamoto, Jieyu Yi, Wenzhi Lin, Brian C. Sales, Jiaqiang Yan, Ryotaro Arita, Jan Kuneš, Anton V. Kozhevnikov, Adolfo G. Eguiluz, Masatoshi Imada, Zheng Gai, Minghu Pan, David G. Mandrus

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Abstract

Particularly in Sr2 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 ∼ 250âmeV) 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.

Original languageEnglish
Article number3073
JournalScientific reports
Volume3
DOIs
Publication statusPublished - 2013 Nov 8
Externally publishedYes

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    Li, Q., Cao, G., Okamoto, S., Yi, J., Lin, W., Sales, B. C., Yan, J., Arita, R., Kuneš, J., Kozhevnikov, A. V., Eguiluz, A. G., Imada, M., Gai, Z., Pan, M., & Mandrus, D. G. (2013). Atomically resolved spectroscopic study of Sr2 IrO 4: Experiment and theory. Scientific reports, 3, [3073]. https://doi.org/10.1038/srep03073