Department of Physics
Condensed Matter Seminar

Multiferroics are materials possessing at least two out of three ferroic properties: electric, magnetic, and elastic. Coupling between different order parameters is the most interesting aspect of multiferroicity and is important for applications. Recently found improper magnetic ferroelectrics show especially strong coupling between ferroelectric and magnetic order parameters. The dynamic magnetoelectric coupling is observed as two distinct phenomena: electromagnon and spin-phonon coupling which correspond to the two lowest coupling terms in the free energy. Although theoretically electromagnons are studied for more than 40 years, only recently electromagnons were observed by the infrared spectroscopy in some RMnO3 [1] and in some RMn2O5 [2] multiferroics. I will review the current state of electromagnon research. Support by the NSF-MRSEC at the University of Maryland, DMR # 0520471 is acknowledged. [1] A. Pimenov, A.A. Mukhin, V.Y. Ivanov, V.D. Travkin, A. Balbashov, and A. Loidl, Nature Phys. 2, (2006) 97. [2] A.B. Sushkov, R. Valdés Aguilar, S. Park, S.W. Cheong, and H.D. Drew, Phys. Rev. Lett., 98 (2007) 027202. [3} See also reviews on electromagnons of these two groups to appear in J. Phys.: Condens. Matter 20 (September 2008).