Directional dichroism in the paramagnetic state of multiferroics: a case study of infrared light absorption in Sr2CoSi2O7 at high temperatures

  • The coexisting magnetic and ferroelectric orders in multiferroic materials give rise to a handful of novel magnetoelectric phenomena, such as the absorption difference for the opposite propagation directions of light called the nonreciprocal directional dichroism (NDD). Usually, these effects are restricted to low temperature, where the multiferroic phase develops. In this paper, we report the observation of NDD in the paramagnetic phase of Sr2CoSi2O7 up to temperatures more than 10 times higher than its Néel temperature (7 K) and in fields up to 30 T. The magnetically induced polarization and NDD in the disordered paramagnetic phase is readily explained by the single-ion spin-dependent hybridization mechanism, which does not necessitate correlation effects between magnetic ions. The Sr2CoSi2O7 provides an ideal system for a theoretical case study, demonstrating the concept of magnetoelectric spin excitations in a paramagnet via analytical as well as numerical approaches. We appliedThe coexisting magnetic and ferroelectric orders in multiferroic materials give rise to a handful of novel magnetoelectric phenomena, such as the absorption difference for the opposite propagation directions of light called the nonreciprocal directional dichroism (NDD). Usually, these effects are restricted to low temperature, where the multiferroic phase develops. In this paper, we report the observation of NDD in the paramagnetic phase of Sr2CoSi2O7 up to temperatures more than 10 times higher than its Néel temperature (7 K) and in fields up to 30 T. The magnetically induced polarization and NDD in the disordered paramagnetic phase is readily explained by the single-ion spin-dependent hybridization mechanism, which does not necessitate correlation effects between magnetic ions. The Sr2CoSi2O7 provides an ideal system for a theoretical case study, demonstrating the concept of magnetoelectric spin excitations in a paramagnet via analytical as well as numerical approaches. We applied exact diagonalization of a spin cluster to map out the temperature and field dependence of the spin excitations, as well as symmetry arguments of the single ion and lattice problem to get the spectrum and selection rules.show moreshow less

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Metadaten
Author:J. Viirok, U. Nagel, T. Rõõm, D. G. Farkas, P. Balla, D. Szaller, V. Kocsis, Y. Tokunaga, Y. Taguchi, Y. Tokura, B. Bernáth, Dmytro KamenskyiORCiDGND, István KézsmárkiORCiDGND, Sándor Bordács, K. Penc
URN:urn:nbn:de:bvb:384-opus4-474375
Frontdoor URLhttps://opus.bibliothek.uni-augsburg.de/opus4/47437
ISSN:2469-9950OPAC
ISSN:2469-9969OPAC
Parent Title (English):Physical Review B
Publisher:American Physical Society (APS)
Type:Article
Language:English
Year of first Publication:2019
Publishing Institution:Universität Augsburg
Release Date:2019/01/25
Volume:99
Issue:1
First Page:014410
DOI:https://doi.org/10.1103/physrevb.99.014410
Institutes:Mathematisch-Naturwissenschaftlich-Technische Fakultät
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik
Mathematisch-Naturwissenschaftlich-Technische Fakultät / Institut für Physik / Lehrstuhl für Experimentalphysik V
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):Deutsches Urheberrecht