Giant AC magnetoresistance and anisotropic AC magnetoresistance in granular magnetic alloys

TL;DR

This study investigates the AC resistance and magnetoresistance in granular magnetic Cu85Co15 ribbons, revealing a giant isotropic effect near magnetic freezing and a newly identified anisotropic AC magnetoresistance influenced by field strength and frequency.

Contribution

It reports the discovery of anisotropic AC magnetoresistance and detailed behavior of giant AC magnetoresistance in granular magnetic alloys, expanding understanding of magnetic response in such materials.

Findings

Giant isotropic AC magnetoresistance peaks near magnetic freezing temperature.

Anisotropic AC magnetoresistance depends on magnetic field strength and frequency.

Resistance behavior varies significantly in different magnetic field regimes.

Abstract

(withdrawn)AC resistance of melt-spun granular magnetic Cu85Co15 ribbons was measured as a function of temperature in the range 5-300 K, magnetic field Hdc in the range -60 kOe to 60 kOe, and frequency in the range 1-1000 Hz. A sharp peak of zero-field resistance, which scales with frequency, and an associated isotropic giant AC magnetoresistance in small fields are observed around the temperature of collective freezing of interacting magnetic moments. Anomalous behavior of AC resistance in large fields (Hdc > 20 kOe) is observed in a much broader temperature range. This effect is not only frequency- dependent, but also highly sensitive to anisotropy. We call it anisotropic AC magnetoresistance.