"Ferro-Electricity in Frustrated Magnets"
Professor Collin Broholm
Department of Physics and Astronomy
Department of Physics
Monday, October 16, 2006
Barus and Holley 168, 4:30 P.M.*
While electrostatics and magnetostatics are disparate phenomena in a vacuum, no symmetry forbids materials from responding magnetically to an electric field or vise versa. Materials with a strong magneto-electric response are of interest for applications and challenge our understanding of magnetic dielectrics. I discuss specific examples of magneto-electricity in metal oxides with triangular or kagomé lattices of spins with competing antiferromagnetic interactions [1-3]. It is shown that inversion symmetry breaking magnetic order can act as an effective electric field through magneto-elastic distortions that relieve frustration. The results presented in this talk are based on magnetic neutron scattering experiments.
 M. Kenzelmann, A. B. Harris, S. Jonas, C. Broholm, J. Schefer, S. B. Kim, C. L. Zhang, S.-W. Cheong, O. P. Vajk, and J. W. Lynn, Phys. Rev. Lett. 95, 087206 (2005).
 G. Lawes, A. B. Harris, T. Kimura, N. Rogado, R. J. Cava, A. Aharony, O. Entin-Wohlman, T. Yildirim, M. Kenzelmann, C. Broholm, and A. P. Ramirez, Phys. Rev. Lett. 95, 087205 (2005).
 M. Kenzelmann, G. Lawes, A.B. Harris, G. Gasparovic, C. Broholm,
A.P. Ramirez, G.A. Jorge, M. Jaime, S. Park, Q. Huang, A.Ya. Shapiro, and
*Refreshments at 4:00 P.M.