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Hallmarks of Hunds coupling in the Mott insulator Ca2RuO4.

ABSTRACT: A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realized in Ca2RuO4. Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic structure. Here we provide-using angle-resolved photoemission electron spectroscopy-the band structure of the paramagnetic insulating phase of Ca2RuO4 and show how it features several distinct energy scales. Comparison to a simple analysis of atomic multiplets provides a quantitative estimate of the Hund's coupling J=0.4 eV. Furthermore, the experimental spectra are in good agreement with electronic structure calculations performed with Dynamical Mean-Field Theory. The crystal field stabilization of the dxy orbital due to c-axis contraction is shown to be essential to explain the insulating phase. These results underscore the importance of multi-band physics, Coulomb interaction and Hund's coupling that together generate the Mott insulating state of Ca2RuO4.

SUBMITTER: Sutter D 

PROVIDER: S-EPMC5424259 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realized in Ca<sub>2</sub>RuO<sub>4</sub>. Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic structure. Here we provide-using angle-resolved photoemission electron spectroscopy-the band structure of the paramagnetic insulating phase of Ca<sub>2</sub>RuO<sub>4</sub> and show how it features several distinct energy sca  ...[more]