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Ultrafast coupled charge and spin dynamics in strongly correlated NiO

  • Gillmeister, Konrad Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany
  • Golež, Denis Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth Avenue, New York NY 10010, USA - Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
  • Chiang, Cheng-Tien Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany
  • Bittner, Nikolaj Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
  • Pavlyukh, Yaroslav Department of Physics, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany
  • Berakdar, Jamal Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany
  • Werner, Philipp Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
  • Widdra, Wolf Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany - Max Planck Institute of Microstructure Physics, 06120 Halle, Germany
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    14.08.2020
Published in:
  • Nature Communications. - 2020, vol. 11, no. 1, p. 4095
English Charge excitations across an electronic band gap play an important role in opto- electronics and light harvesting. In contrast to conventional semiconductors, studies of above-band-gap photoexcitations in strongly correlated materials are still in their infancy. Here we reveal the ultrafast dynamics controlled by Hund’s physics in strongly correlated photoexcited NiO. By combining time-resolved two-photon photoemission experiments with state-of-the-art numerical calculations, an ultrafast (≲10 fs) relaxation due to Hund excitations and related photo-induced in-gap states are identified. Remarkably, the weight of these in-gap states displays long-lived coherent THz oscillations up to 2 ps at low temperature. The frequency of these oscillations corresponds to the strength of the antiferromagnetic superexchange interaction in NiO and their lifetime vanishes slightly above the Néel temperature. Numerical simulations of a two-band t-J model reveal that the THz oscillations originate from the interplay between local many-body excitations and antiferromagnetic spin correlations.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
  • English
Classification
Physics
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/308820
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