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"Ferro-Electricity in Frustrated Magnets" Professor Collin Broholm Department of Physics and Astronomy Department of Physics COLLOQUIUM
Monday, October 16, 2006
Barus and Holley 168, 4:30 P.M.*
ABSTRACT 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 *Refreshments at 4:00 P.M. |