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Late submission for announcement of Colloquium at Brown Physics D epartment on Monday 10/16

"Ferro-Electricity in Frustrated Magnets"


Professor Collin Broholm


Department of Physics and Astronomy

Johns Hopkins university




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.

 [1] 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).

 [2] 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).

[3] 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 L.A. Demianets, Submitted to Nature (2006).



*Refreshments at 4:00 P.M.