Aging, rejuvenation and memory effects in re-entrant ferromagnets

TL;DR

This study investigates the slow magnetic dynamics, aging, rejuvenation, and memory effects in re-entrant ferromagnets, revealing how disorder influences these phenomena through experimental ac susceptibility and magnetization measurements.

Contribution

It provides new experimental evidence on aging and memory effects in re-entrant ferromagnets and links these to hierarchical domain wall reconformations influenced by disorder.

Findings

Rejuvenation effect observed in all samples.

Memory effect increases with higher dilution.

Supports hierarchical domain wall reconformation model.

Abstract

We have studied the slow dynamics of the ferromagnetic phases of the re-entrant CdCr_{2x}In_{2-2x}S_4 system for 0.85<x<=1 by means of low frequency ac susceptibility and magnetization measurements. Experimental procedures widely used in the investigation of the out-of-equilibrium dynamics of spin glasses (such as the x=0.85 compound) have been applied to search for aging, rejuvenation and memory effects, and to test their dependence on the disorder introduced by dilution of the magnetic ions. Whereas the rejuvenation effect is found in all studied samples, the memory effect is clearly enhanced for increasing dilutions. The results support a description of aging in both ferromagnetic and re-entrant spin-glass phases in terms of hierarchical reconformations of domain walls pinned by the disorder.