next Q-MAC meetings in 2018:

3rd Q-MAC symposium in Venice, May 22-25, 2018.

Next regular meeting in Paris,       November 27-28, 2018.

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Antoine Georges leads the CCQ in New York

at the newly founded Flatiron Institute of the Simons Foundation.

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Publication Detail / Abstract

D. Sutter, C.G. Fatuzzo, S. Moser, M. Kim, R. Fittipaldi, A. Vecchione, V. Granata, Y. Sassa, F. Cossalter, G. Gatti, M. Grioni, H.M. Ronnow, N.C. Plumb, C.E. Matt, M. Shi, M. Hoesch, T.K. Kim, T.R. Chang, H.T. Jeng, C. Jozwiak, A. Bostwick, E. Rotenberg, A. Georges, T. Neupert, J. Chang

Hallmarks of Hund's coupling in the Mott insulator Ca2RuO4

> Full text via publisher
A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realised 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 stabilisation of the dxy orbital due to c-axis contraction is shown to be important in explaining the nature of the insulating state. It is thus a combination of multiband physics, Coulomb interaction and Hund's coupling that generates the Mott insulating state of Ca2RuO4. These results underscore the importance of Hund's coupling in the ruthenates and related multiband materials.
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