Influence of Demagnetization Effect on the Kinetics of the Itinerant Electron Metamagnetic Transition in Magnetic Refrigerant ${\rm La}{({\rm Fe}_{0.88}{\rm Si}_{0.12})}_{13}$

Influence of demagnetization effect on the kinetics of the itinerant electron metamagnetic (IEM) transition in magnetic refrigerant La(Fe_0.88Si_0.12)₁₃ has been investigated by both the static and time-dependent magnetization measurements. From the magnetization measurement by changing the field direction against the longitudinal direction of specimen, the critical magnetic field μ₀HC for the IEM transition becomes larger in the setup with a higher demagnetization coefficient. The time dependence of magnetization under constant magnetic field indicates that the progress of both the onset and offset of the IEM transition is completed in the condition with smaller demagnetization effect, meanwhile the arrest of progress is elicited by the larger demagnetization effect. In addition, the Johnson-Mehl-Avrami analysis leads to a 2-D-like growth of the ferromagnetic phase in the paramagnetic matrix. These results reveal that the nucleation and growth process of the IEM transition is affected by the demagnetization effect.