Anomaly of AC resistance in magnetic nanoparticle alloys at spin-glass-like transition

TL;DR

This study investigates the AC resistance anomaly in Cu-Co magnetic alloys at the spin-glass-like transition, revealing a sharp resistance maximum linked to magnetic freezing and giant magnetoresistance effects.

Contribution

It introduces a model connecting AC resistance peaks to diverging correlation lengths and provides experimental determination of critical exponents at the transition.

Findings

AC resistance exhibits a sharp maximum at transition temperature

Giant AC magnetoresistance observed at freezing point

Model allows direct extraction of critical exponents

Abstract

(withdrawn) A combined study of magnetic susceptibility and AC resistance was performed on melt-spun Cu-Co granular magnetic ribbons. The AC resistance as a function of temperature has a sharp maximum. We associate it with a diverging correlation length at the temperature of collective freezing of magnetic moments via increasing magnetic losses in the induced non-uniform field. Application of this model to the experimental data allows a direct determination of the critical exponent of correlation length on both sides of the transition. Giant AC magnetoresistance is observed at the freezing temperature.