Spin dynamical phase and anti-resonance in a strongly coupled   magnon-photon system
  We experimentally studied a strongly coupled magnon-photon system via microwave transmission measurements. An anti-resonance, i.e. the suppression of the microwave transmission, is observed, indicating a relative phase change between the magnon response and the driving microwave field. We show that this anti-resonance feature can be used to interpret the phase evolution of the coupled magnon-microwave system and apply this technique to reveal the phase evolution of magnon dark modes. Our work provides a standard procedure for the phase analysis of strongly coupled systems, enabling the phase characterization of each subsystem, and can be generally applied to other strongly coupled systems. 
Michael Harder, Paul Hyde, Lihui Bai, Christophe Match and Can-Ming Hu
cond-mat.mtrl-sci cond-mat.mes-hall