Electrically active magnetic excitations in antiferromagnets

Operating magnetic resonance by an electric field is a highly nontrivial concept, but is the most demanding function in the future of spin-electronics. Recent observations in a variety of multiferroic materials, named 'collective electrically active magnetic excitations' and frequently referred to as electromagnons, reveal a possibility of implementing such a function. Experimental advances in terahertz spectroscopy of electromagnons in multiferroics, as well as related theoretical models, are reviewed. Earlier theoretical works, where the existence of electric-dipole-active magnetic excitations in antiferro- and ferrimagnets with collinear spin structure has been predicted, are also discussed. Multi-sublattice magnets with electrically active magnetic excitations at room temperature provide a direct opportunity to transform one type of excitation into another in a terahertz time-domain. This is of crucial importance for magnon-based spintronics, since only short-wavelength exchange magnons allow signal processing at nanoscale distances. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752093]