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Wednesday, May 22

Magnetic Structure and Electric Field Effects in Multiferroic BiFeO3

Valery Kiryukhin, Rutgers University, New Jersey
Materials Science and Technology Division, Materials Theory Group, Seminar
11:00 AM — 12:00 PM, Chemical and Material Sciences Building (4100), Room J-302
Contact: Randy Fishman (fishmanrs@ornl.gov), 865.574.5786

Abstract

BiFeO3 (BFO) is a room-temperature multiferroic combining large electric polarization with a "tilted" anharmonic magnetic cycloid. In this talk, we discuss various ways of controlling magnetism in BFO single crystals using coupling between the ferroelectric and magnetic order parameters.

Elastic and inelastic neutron scattering, as well as SANS, are used, and electric and magnetic fields are applied in-situ. Electric field can rotate the electric polarization and Fe spins simultaneously, and a chiral magnetic monodomain state can be obtained. Populations of the 3 equivalent cycloidal magnetic domains can be controlled by an electric field through piezoelectric coupling. Alternatively, the domains can be controlled via the inverse effect by applying uniaxial pressure. Magnetic excitation spectra are presented, and effects of an electric field on the magnetic excitations are discussed. The ability to control the magnetic domains and excitations by an electric field or tiny deformation accentuates the potential of BFO for room-temperature applications involving magnetoelectric effects.