Magnon Polarons in the Spin Seebeck Effect
  Sharp structures in magnetic field-dependent spin Seebeck effect (SSE) voltages of Pt/Y$_{3}$Fe$_{5}$O$_{12}$ (YIG) at low temperatures are attributed to the magnon-phonon interaction. Experimental results are well reproduced by a Boltzmann theory that includes the magnetoelastic coupling (MEC). The SSE anomalies coincide with magnetic fields tuned to the threshold of magnon-polaron formation. The effect gives insight into the relative quality of the lattice and magnetization dynamics. 
Takashi Kikkawa, Ka Shen, Benedetta Flebus, Rembert A. Duine, Ken-ichi   Uchida, Zhiyong Qiu, Gerrit E. W. Bauer, Eiji Saitoh
cond-mat.mtrl-sci