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arXiv · 2404.12646

Fingerprints of Mott and Slater gaps in the core-level photoemission spectra of antiferromagnetic iridates

K. Nakagawa·A. Hariki·T. Okauchi·H. Fujiwara·K. -H. Ahn·Y. Murakami·S. Hamamoto·Y. Kanai-Nakata·T. Kadono·A. Higashiya·K. Tamasaku·M. Yabashi·T. Ishikawa·A. Sekiyama·S. Imada·J. Kuneš·K. Takase·A. Yamasaki
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Abstract

We present Ir $4f$ core-level hard-x-ray photoemission spectroscopy (HAXPES) experiments conducted across antiferromagnetic (AFM) ordering transition in Ruddlesden-Popper iridates Sr$_2$IrO$_4$ and Sr$_3$Ir$_2$O$_7$. The Ir $4f$ spectra exhibit distinct changes between the AFM and paramagnetic (PM) phases, with the spectral difference $I_\text{PM}-I_\text{AFM}$ showing a contrasting behavior in the two compounds. By employing computational simulations using the local-density approximation combined with the dynamical mean-field theory method, we elucidate that $I_\text{PM}-I_\text{AFM}$ primary reflects the Slater or Mott-Hubbard character of the AFM insulating state rather than material specific details. This sensitivity to fine low-energy electronic structure arises from the dependence of charge-transfer responses to the sudden creation of a localized core hole on both metal-insulator transitions and long-range AFM ordering. Our result broadens the applications of core-level HAXPES as a tool for characterization of electronic structure.

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K. Nakagawa, A. Hariki, T. Okauchi, H. Fujiwara, K. -H. Ahn, Y. Murakami, S. Hamamoto, Y. Kanai-Nakata, T. Kadono, A. Higashiya, K. Tamasaku, M. Yabashi, T. Ishikawa, A. Sekiyama, S. Imada, J. Kuneš, K. Takase, A. Yamasaki. 2024-04-19. Fingerprints of Mott and Slater gaps in the core-level photoemission spectra of antiferromagnetic iridates. https://doi.org/10.1103/physrevb.111.195114

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