Several recently reported exciting phenomena such as spin caloritronics or ultrafast laser-induced spin dynamics
involve the action of temperature on spin dynamics. However, the inverse effect of magnetization dynamics on
temperature change is very frequently ignored. Based on the density matrix approach, in this work we derive
a self-consistent model for describing the magnetization and phonon temperature dynamics in ferromagnets
in the framework of the quantum Landau-Lifshitz-Bloch equation. We explore potential applicability of our
approach for two cases, inspired by magnetocaloric effect and magnetic fluid hyperthermia. In the first case, the
spin-phonon dynamics is governed by the longitudinal relaxation in bulk systems close to the Curie temperature;
while in the second case it is described by the transverse relaxation during the hysteresis cycle of individual
nanoparticles well below the Curie temperature.
