Spin glass behavior in an interacting gamma-Fe2O3 nanoparticle system

TL;DR

This study explores the superspin glass behavior in a concentrated maghemite nanoparticle system, revealing similarities to atomic spin glasses and analyzing aging and scaling laws to understand the underlying magnetic interactions.

Contribution

It provides the first detailed comparison of superspin glass behavior in nanoparticle assemblies with atomic spin glasses, including aging dynamics and scaling law analysis.

Findings

Superspin glass transition occurs at low temperature.

Scaling laws for superspin glasses match atomic spin glasses after correction.

Superparamagnetic contributions influence the superspin glass response.

Abstract

In this paper we investigate the superspin glass behavior of a concentrated assembly of interacting maghemite nanoparticles and compare it to that of canonical atomic spin glass systems. ac versus temperature and frequency measurements show evidence of a superspin glass transition taking place at low temperature. In order to fully characterize the superspin glass phase, the aging behavior of both the thermo-remanent magnetization (TRM) and ac susceptibility has been investigated. It is shown that the scaling laws obeyed by superspin glasses and atomic spin glasses are essentially the same, after subtraction of a superparamagnetic contribution from the superspin glass response functions. Finally, we discuss a possible origin of this superparamagnetic contribution in terms of dilute spin glass models.