Reversal-Field Memory in the Hysteresis of Spin Glasses

TL;DR

This paper introduces the reversal-field memory effect in spin glasses, revealing a unique hysteresis singularity linked to symmetric spin clusters, characterized using FORC diagrams and compared with experimental magnetic films.

Contribution

It uncovers a new hysteresis singularity in spin glasses caused by symmetric spin clusters and demonstrates the effectiveness of FORC diagrams as a magnetic fingerprinting tool.

Findings

Reversal-field memory effect causes non-analyticity in magnetization curves.

FORC diagrams effectively characterize the reversal-field memory effect.

Comparison with experiments on magnetic films validates the theoretical findings.

Abstract

We report a novel singularity in the hysteresis of spin glasses, the reversal-field memory effect, which creates a non-analyticity in the magnetization curves at a particular point related to the history of the sample. The origin of the effect is due to the existence of a macroscopic number of "symmetric clusters" of spins associated with a local spin-reversal symmetry of the Hamiltonian. We use First Order Reversal Curve (FORC) diagrams to characterize the effect and compare to experimental results on thin magnetic films. We contrast our results on spin glasses to random magnets and show that the FORC technique is an effective "magnetic fingerprinting" tool.