Thermodynamics of the Heat-Flux Avalanches at the First-Order Magnetic Transition in Magnetocaloric Materials

We investigate the kinetics of first-order magnetic phase transitions by measuring and modeling the heat-flux avalanches corresponding to the irreversible motion of the phase-boundary interface separating the coexisting low- and high-temperature stable magnetic phases. By means of out-of-equilibrium thermodynamics, we encompass the damping mechanisms of the boundary motion in a phenomenological parameter ?s. By analyzing the time behavior of the heat-flux signals measured on La(Fe-Mn-Si)13-H magnetocaloric compounds through Peltier calorimetry temperature scans performed at low rates, we relate the linear rise of the individual avalanches to the intrinsic-damping parameter ?s.