Magnetic Avalanches in Molecular Nanomagnets

TL;DR

This paper reviews experimental findings on magnetic avalanches in molecular nanomagnets, focusing on ignition temperatures and propagation speeds, and compares them with theoretical models of magnetic deflagration.

Contribution

It provides a comprehensive review of experimental data on magnetic avalanches and evaluates their consistency with existing theoretical models, highlighting areas of incomplete understanding.

Findings

Qualitative agreement between data and magnetic deflagration theory

Discrepancies in numerical predictions suggest incomplete understanding

Experimental results on ignition temperature and avalanche speed

Abstract

The magnetization of the prototypical molecular magnet Mn12-acetate exhibits a series of sharp steps at low temperatures due to quantum tunneling at specific resonant values of magnetic field applied along the easy c-axis. An abrupt reversal of the magnetic moment of such a crystal can also occur as an avalanche, where the spin reversal proceeds along a "deflagration" front that travels through the sample at subsonic speed. In this article we review experimental results that have been obtained for the ignition temperature and the speed of propagation of magnetic avalanches in molecular nanomagnets. Fits of the data with the theory of magnetic deflagration yield overall qualitative agreement. However, numerical discrepancies indicate that our understanding of these avalanches is incomplete.