Ultrafast coupled charge and spin dynamics in strongly correlated NiO

Gillmeister, Konrad; Golež, Denis; Chiang, Cheng-Tien; Bittner, Nikolaj; Pavlyukh, Yaroslav; Berakdar, Jamal; Werner, Philipp; Widdra, Wolf

doi:10.1038/s41467-020-17925-8

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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

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

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