Field sweep rate dependence of the coercive field of single-molecule magnets: a classical approach with applications to the quantum regime

TL;DR

This paper introduces a classical model-based method to analyze how the coercive field of single-molecule magnets depends on the field sweep rate, aiding the understanding of their magnetic properties and quantum behavior.

Contribution

A novel approach applying the Neel-Brown model to determine key magnetic parameters of SMMs, including those lacking quantum tunneling features.

Findings

Determined energy barriers and anisotropy constants for Mn12 and Mn84.

Identified crossover temperature from classical to quantum regimes.

Provided a method applicable to large SMMs without quantum tunneling steps.

Abstract

A method, based on the Neel-Brown model of thermally activated magnetization reversal of a magnetic single-domain particle, is proposed to study the field sweep rate dependence of the coercive field of single-molecule magnets (SMMs). The application to Mn12 and Mn84 SMMs allows the determination of the important parameters that characterize the magnetic properties: the energy barrier, the magnetic anisotropy constant, the spin, tau_0, and the crossover temperature from the classical to the quantum regime. The method may be particularly valuable for large SMMs that do not show quantum tunneling steps in the hysteresis loops.