Magnetization Process of Single Molecule Magnets at Low Temperatures

TL;DR

This paper investigates the magnetization dynamics of single molecule magnets at very low temperatures, revealing lattice-dependent behaviors and the influence of initial correlations on the magnetization process.

Contribution

It demonstrates how pre-quench correlations influence magnetization and identifies different time-dependent behaviors across lattice types, with specific power laws and saturation levels.

Findings

In SC lattices, magnetization follows a sqrt(t) law for a specific time range.

In BCC and FCC lattices, magnetization follows a t^p law with p approximately 0.7.

The final magnetization level depends on lattice structure and magnetic field parameters.

Abstract

We show that correlations established before quenching to very low temperatures, later drive the magnetization process of systems of single molecule magnets, after a magnetic field is applied at t=0. We also show that in SC lattices, m \propto sqrt(t), as observed in Fe_8, but only for 1+2*log_10(h_d/h_w) time decades, where h_d is a nearest neighbor dipolar magnetic field and a spin reversal can occur only if the field on it is within (-h_w,h_w). However, the sqrt(t) behavior is not universal. For BCC and FCC lattices, m \propto t^p, but p \simeq 0.7. The value to which m finally levels off is also given.