College Park, Maryland      June 6 - 10 , 2004

M3-C4 (2:30 PM): Magnetic Excitations in Hexagonal Ferroelectric HoMnO3

O. P. Vajk, J. W. Lynn (NIST Center for Neutron Research), S.-W. Cheong (Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA), S.B. Kim (Rutgers University), C. Broholm (Department of Physics & Astronomy, Johns Hopkins University), M. Kenzelmann (NIST Center for Neutron Research)

Materials with both magnetic and ferroelectric order are of great interest because of their potential applications as well as the novel physics that may result from the interplay of these two phenomena. Hexagonal HoMnO3 is a frustrated antiferromagnet with a complex magnetic phase diagram as well as strong ferroelectric order. Anomalies in the dielectric constant at magnetic phase transitions have shown a coupling of the ferroelectricity to the magnetic order. We have performed neutron scattering experiments on single-crystal HoMnO3. Order parameter measurements are used to measure the multiple magnetic phase transitions, and inelastic measurements reveal a mostly two-dimensional excitation spectrum. Details of the magnetic field, electric field, and temperature dependence of the magnetic properties will be discussed.

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