Magnetic Structure and Magnetoelectric Coupling in Bulk and Thin Film FeVO4

We have investigated the magnetoelectric and magnetodielectric response in FeVO4, which exhibits a change in magnetic structure coincident with ferroelectric ordering at TN2≈15 K. Using symmetry considerations, we construct a model for the possible magnetoelectric coupling in this system and present a discussion of the allowed spin structures in FeVO4. Based on this model, in which the spontaneous polarization is caused by a trilinear spin-phonon interaction, we experimentally explore the magnetoelectric coupling in FeVO4 thin films through measurements of the electric field-induced shift of the multiferroic phase transition temperature, which exhibits an increase of 0.25 K in an applied field of 4 MV/m. The strong spin-charge coupling in FeVO4 is also reflected in the significant magnetodielectric shift, which is present in the paramagnetic phase due to a quartic spin-phonon interaction and shows a marked enhancement with the onset of magnetic order which we attribute to the trilinear spin-phonon interaction. We observe a clear magnetic field-induced dielectric anomaly at lower temperatures, distinct from the sharp peak associated with the multiferroic transition, which we tentatively assign to a spin-reorientation crossover. We also present a magnetoelectric phase diagram for FeVO4. Disciplines Physics | Quantum Physics This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/324 Magnetic structure and magnetoelectric coupling in bulk and thin film FeVO4 A. Dixit,1 G. Lawes,1 and A. B. Harris2 1Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201, USA 2Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Received 1 June 2010; published 29 July 2010 We have investigated the magnetoelectric and magnetodielectric response in FeVO4, which exhibits a change in magnetic structure coincident with ferroelectric ordering at TN2 15 K. Using symmetry considerations, we construct a model for the possible magnetoelectric coupling in this system and present a discussion of the allowed spin structures in FeVO4. Based on this model, in which the spontaneous polarization is caused by a trilinear spin-phonon interaction, we experimentally explore the magnetoelectric coupling in FeVO4 thin films through measurements of the electric field-induced shift of the multiferroic phase transition temperature, which exhibits an increase of 0.25 K in an applied field of 4 MV/m. The strong spin-charge coupling in FeVO4 is also reflected in the significant magnetodielectric shift, which is present in the paramagnetic phase due to a quartic spin-phonon interaction and shows a marked enhancement with the onset of magnetic order which we attribute to the trilinear spin-phonon interaction. We observe a clear magnetic field-induced dielectric anomaly at lower temperatures, distinct from the sharp peak associated with the multiferroic transition, which we tentatively assign to a spin-reorientation crossover. We also present a magnetoelectric phase diagram for FeVO4. DOI: 10.1103/PhysRevB.82.024430 PACS number s : 75.85. t, 77.55.Nv, 75.25. j