Exchange Magnon-Polaritons in Microwave Cavities
  We formulate a scattering theory to study magnetic films in microwave cavities beyond the independent-spin and rotating wave approximations of the Tavis-Cummings model. We demonstrate that strong coupling can be realized not only for the ferromagnetic resonance (FMR) mode, but also for spin wave resonances (SWRs); the coupling strengths are mode dependent and decrease with increasing mode index. The strong coupling regime can be also accessed electrically by spin pumping into a metal contact. 
Yunshan Cao, Peng Yan, Hans Huebl, Sebastian T.B. Goennenwein, Gerrit   E.W. Bauer
cond-mat.mes-hall cond-mat.mtrl-sci