Determination of the magnetic order and the crystal symmetry in the multiferroic ground state of Ba2CoGe2O7

  • Detailed structural investigation of Ba2CoGe2O7 was performed in its low-temperature multiferroic state combining neutron diffraction with magnetization measurements and the optical study of lattice vibrations on single crystals. The crystal structure above (10.4 K) and the crystal and magnetic structures below (2.2 K) the antiferromagnetic transition temperature of TN = 6.7 K were determined using neutron diffraction. The tetragonal space group (SG) P-421m, corresponding to the average structure at room temperature, was found to also describe the structure at low temperatures well. Neutron diffraction data and infrared phonon mode analysis imply no structural phase transition down to 2.2 K. Orthorhombic polar SG Cmm2 is proposed as a true crystal structure. Below TN, the spins of the Co2+ ions form a square-lattice Néel order within the (a,b) plane, while their alignment is ferromagnetic along the c axis. The magnitude of the ordered moment, fully lying within the (a,b) plane, isDetailed structural investigation of Ba2CoGe2O7 was performed in its low-temperature multiferroic state combining neutron diffraction with magnetization measurements and the optical study of lattice vibrations on single crystals. The crystal structure above (10.4 K) and the crystal and magnetic structures below (2.2 K) the antiferromagnetic transition temperature of TN = 6.7 K were determined using neutron diffraction. The tetragonal space group (SG) P-421m, corresponding to the average structure at room temperature, was found to also describe the structure at low temperatures well. Neutron diffraction data and infrared phonon mode analysis imply no structural phase transition down to 2.2 K. Orthorhombic polar SG Cmm2 is proposed as a true crystal structure. Below TN, the spins of the Co2+ ions form a square-lattice Néel order within the (a,b) plane, while their alignment is ferromagnetic along the c axis. The magnitude of the ordered moment, fully lying within the (a,b) plane, is found to be 2.9(1) μB/Co2+ and the easy axis of the sublattice magnetizations corresponds to the [110] direction. A noncollinear spin structure due to small canting is allowed.show moreshow less

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Metadaten
Author:V. Hutanu, A. Sazonov, M. Meven, H. Murakawa, Y. Tokura, Sándor Bordács, István KézsmárkiORCiDGND, B. Náfrádi
URN:urn:nbn:de:bvb:384-opus4-437063
Frontdoor URLhttps://opus.bibliothek.uni-augsburg.de/opus4/43706
ISSN:1098-0121OPAC
ISSN:1550-235XOPAC
Parent Title (English):Physical Review B
Publisher:American Physical Society (APS)
Type:Article
Language:English
Year of first Publication:2012
Publishing Institution:Universität Augsburg
Release Date:2018/11/19
Volume:86
Issue:10
First Page:104401
DOI:https://doi.org/10.1103/physrevb.86.104401
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