Low-Temperature Magnetization Dynamics of Magnetic Molecular Solids in a Swept Field

TL;DR

This study uses Monte Carlo simulations and a kinetic equation to analyze the low-temperature magnetization dynamics of magnetic molecular solids like Fe8 under swept magnetic fields, achieving good experimental agreement.

Contribution

It introduces a kinetic equation for magnetization dynamics in molecular solids and validates it against Monte Carlo simulations and experimental data.

Findings

Simulations match experimental magnetization curves quantitatively.

The kinetic equation accurately predicts behavior except at very low sweep velocities.

Short-range dipolar correlations are significant at low sweep velocities.

Abstract

The swept-field experiments on magnetic molecular solids such as \Fe8 are studied using Monte Carlo simulations. A kinetic equation is developed to understand the phenomenon. It is found that the simulations provide a quantitatively accurate account of the experiments. The kinetic equation provides a similarly accurate account except at very low sweep velocities, where it fails modestly. This failure is due to the neglect of short-range correlations between the dipolar magnetic fields seen by the molecular spins. Both the simulations and the kinetic equation provide a good understanding of the distribution of these dipolar fields.