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

TL;DR

This study uses Monte Carlo simulations to analyze the decay of metastable states in a Blume-Capel ferromagnetic needle, revealing multiple crossover behaviors and the influence of anisotropy on relaxation dynamics.

Contribution

It reports the novel observation of multiple crossovers in metastable decay and precisely estimates crossover times and exponents in a Blume-Capel model.

Findings

Multiple crossovers in metastable decay observed

Crossover times and exponents estimated accurately

Relaxation time depends on anisotropy strength

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 relaxation time was found to depend on the strength of anisotropy.