Multiple crossover in the decay of metastable volume fraction of a Blume-Capel ferromagnetic needle

Ishita Tikader, Muktish Acharyya

Published: 2025/8/21

Abstract

The transient behaviours of a Blume-Capel ferromagnetic needle have been studied extensively by Monte-Carlo simulation. The needle has an elongated length in one direction compared to its cross-section. In the context of transient behaviour, we have captured the decay of the metastable state and the magnetic relaxation behaviours in our study. The dependence of metastable behaviour with anisotropy (single site) has been studied. \emph{Interestingly, we have observed multiple (different values of $n$ in different time domains) crossover in the decay of metastable volume fraction (obeying Avrami's law $\beta \sim {\rm exp}(-Kt^n)$). We have identified the crossover time, and the values of $n$ are estimated precisely.} The mean (magnetic) reversal time has been studied as a function of anisotropy. It is observed to be almost independent of anisotropy for its negative value; however, it is found to decrease exponentially with positive anisotropy. The exponential relaxation behaviour (in the corresponding paramagnetic phase) is observed. The range of the relaxation time is observed to decrease as the temperature increases.