title: FeCr₂S₄ in magnetic fields: possible evidence for a multiferroic ground state.
abstract: We report on neutron diffraction, thermal expansion, magnetostriction, dielectric, and specific heat measurements on polycrystalline FeCr2S4 in external magnetic fields. The ferrimagnetic ordering temperatures TC ≈ 170 K and the transition at TOO ≈ 10 K, which has been associated with orbital ordering, are only weakly shifted in magnetic fields up to 9 T. The cubic lattice parameter is found to decrease when entering the state below TOO. The magnetic moments of the Cr- and Fe-ions are reduced from the spin-only values throughout the magnetically ordered regime, but approach the spin-only values for fields >5.5 T. Thermal expansion in magnetic fields and magnetostriction experiments indicate a contraction of the sample below about 60 K. Below TOO this contraction is followed by a moderate expansion of the sample for fields larger than ~4.5 T. The transition at TOO is accompanied by an anomaly in the dielectric constant. The dielectric constant depends on both the strength and orientation of the external magnetic field with respect to the applied electric field for T < TOO. A linear correlation of the magnetic-field-induced change of the dielectric constant and the magnetic-field dependent magnetization is observed. This behaviour is consistent with the existence of a ferroelectric polarization and a multiferroic ground state below 10 K.
authors.affiliation: 1] The School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia [2] Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Bertinshaw
authors.affiliation: 1] The School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia [2] Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Ulrich
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Günther
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Schrettle
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Wohlauer
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Krohns
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Reehuis
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Studer
authors.affiliation: Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Avdeev
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA.
authors.forename: D V
authors.initials: DV
authors.lastname: Quach
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Groza
authors.affiliation: 1] Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany [2] Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, Republic of Moldova.
authors.forename: V
authors.initials: V
authors.lastname: Tsurkan
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Loidl
authors.affiliation: Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Deisenhofer