Spin-Charge-Lattice Coupling through Resonant Multi-Magnon Excitations   in Multiferroic BiFeO3
  Spin-charge-lattice coupling mediated by multi-magnon processes is demonstrated in multiferroic BiFeO3. Experimental evidence of two and three magnons excitations as well as multimagnon coupling at electronic energy scales and high temperatures are reported. Temperature dependent Raman experiments show up to five resonant enhancements of the 2-magnon excitation below the Neel temperature. These are shown to be collective interactions between on-site Fe d-d electronic resonance, phonons and multimagnons 
M. O. Ramirez, A. Kumar, S. A. Denev, Y. H. Chu, J. Seidel, L. Martin,   S-Y. Yang R. C. Rai, X. Xue, J. F. Ihlefeld, N. Pod...