Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4

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. Rønnow, N. C. Plumb, C. E. Matt, M. Shi, M. Hoesch, T. K. Kim, T. R. Chang, H. T. Jeng, C. JozwiakA. Bostwick, E. Rotenberg, A. Georges, T. Neupert, J. Chang

Research output: Contribution to journalArticle

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Abstract

A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realised in Ca$_2$RuO$_4$. 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$_2$RuO$_4$ 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 d$_{xy}$ 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 Ca$_2$RuO$_4$. These results underscore the importance of Hund's coupling in the ruthenates and related multiband materials.
Original languageEnglish
JournalNature Communications
Volume8
DOIs
Publication statusPublished - 2017 May 5

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Physics
Electronic structure
insulators
Photoelectron Spectroscopy
Mean field theory
Electron spectroscopy
Orbit
Photoelectron spectroscopy
Coulomb interactions
Band structure
Orbits
Stabilization
Electrons
electronic structure
Crystals
physics
contraction
crystal field theory
electron spectroscopy
photoelectric emission

Cite this

Sutter, D. ; Fatuzzo, C. G. ; Moser, S. ; Kim, M. ; Fittipaldi, R. ; Vecchione, A. ; Granata, V. ; Sassa, Y. ; Cossalter, F. ; Gatti, G. ; Grioni, M. ; Rønnow, H. M. ; Plumb, N. C. ; Matt, C. E. ; Shi, M. ; Hoesch, M. ; Kim, T. K. ; Chang, T. R. ; Jeng, H. T. ; Jozwiak, C. ; Bostwick, A. ; Rotenberg, E. ; Georges, A. ; Neupert, T. ; Chang, J. / Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4. In: Nature Communications. 2017 ; Vol. 8.
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title = "Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4",
abstract = "A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realised in Ca$_2$RuO$_4$. 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$_2$RuO$_4$ 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 d$_{xy}$ 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 Ca$_2$RuO$_4$. These results underscore the importance of Hund's coupling in the ruthenates and related multiband materials.",
author = "D. Sutter and Fatuzzo, {C. G.} and S. Moser and M. Kim and R. Fittipaldi and A. Vecchione and V. Granata and Y. Sassa and F. Cossalter and G. Gatti and M. Grioni and R{\o}nnow, {H. M.} and Plumb, {N. C.} and Matt, {C. E.} and M. Shi and M. Hoesch and Kim, {T. K.} and Chang, {T. R.} and Jeng, {H. T.} and C. Jozwiak and A. Bostwick and E. Rotenberg and A. Georges and T. Neupert and J. Chang",
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Sutter, D, Fatuzzo, CG, Moser, S, Kim, M, Fittipaldi, R, Vecchione, A, Granata, V, Sassa, Y, Cossalter, F, Gatti, G, Grioni, M, Rønnow, HM, Plumb, NC, Matt, CE, Shi, M, Hoesch, M, Kim, TK, Chang, TR, Jeng, HT, Jozwiak, C, Bostwick, A, Rotenberg, E, Georges, A, Neupert, T & Chang, J 2017, 'Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4', Nature Communications, vol. 8. https://doi.org/10.1038/ncomms15176

Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4. / Sutter, D.; Fatuzzo, C. G.; Moser, S.; Kim, M.; Fittipaldi, R.; Vecchione, A.; Granata, V.; Sassa, Y.; Cossalter, F.; Gatti, G.; Grioni, M.; Rønnow, H. M.; Plumb, N. C.; Matt, C. E.; Shi, M.; Hoesch, M.; Kim, T. K.; Chang, T. R.; Jeng, H. T.; Jozwiak, C.; Bostwick, A.; Rotenberg, E.; Georges, A.; Neupert, T.; Chang, J.

In: Nature Communications, Vol. 8, 05.05.2017.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4

AU - Sutter, D.

AU - Fatuzzo, C. G.

AU - Moser, S.

AU - Kim, M.

AU - Fittipaldi, R.

AU - Vecchione, A.

AU - Granata, V.

AU - Sassa, Y.

AU - Cossalter, F.

AU - Gatti, G.

AU - Grioni, M.

AU - Rønnow, H. M.

AU - Plumb, N. C.

AU - Matt, C. E.

AU - Shi, M.

AU - Hoesch, M.

AU - Kim, T. K.

AU - Chang, T. R.

AU - Jeng, H. T.

AU - Jozwiak, C.

AU - Bostwick, A.

AU - Rotenberg, E.

AU - Georges, A.

AU - Neupert, T.

AU - Chang, J.

PY - 2017/5/5

Y1 - 2017/5/5

N2 - A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realised in Ca$_2$RuO$_4$. 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$_2$RuO$_4$ 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 d$_{xy}$ 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 Ca$_2$RuO$_4$. These results underscore the importance of Hund's coupling in the ruthenates and related multiband materials.

AB - A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realised in Ca$_2$RuO$_4$. 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$_2$RuO$_4$ 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 d$_{xy}$ 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 Ca$_2$RuO$_4$. These results underscore the importance of Hund's coupling in the ruthenates and related multiband materials.

U2 - 10.1038/ncomms15176

DO - 10.1038/ncomms15176

M3 - Article

VL - 8

JO - Nature Communications

JF - Nature Communications

SN - 2041-1723

ER -

Sutter D, Fatuzzo CG, Moser S, Kim M, Fittipaldi R, Vecchione A et al. Hallmarks of Hunds coupling in the Mott insulator Ca 2 RuO 4. Nature Communications. 2017 May 5;8. https://doi.org/10.1038/ncomms15176