Memory and aging effects in antiferromagnetic nanoparticles

TL;DR

This study explores the slow magnetic dynamics, memory, and aging effects in antiferromagnetic NiO nanoparticles, revealing size-dependent behaviors and differences from ferromagnetic particles.

Contribution

It provides new insights into the size-dependent magnetic memory and aging effects specific to antiferromagnetic nanoparticles, highlighting differences from ferromagnetic counterparts.

Findings

Stronger memory effects in small antiferromagnetic nanoparticles.

Reversal of memory effect strength with increasing particle size.

Distinct two-step relaxation behavior in thermoremanent magnetization.

Abstract

We investigate slow dynamics of collection of a few antiferromagnetic NiO nanoparticles. The zero-field cooled magnetization exhibits size dependent fluctuations. We find memory effects in field cooled magnetization, as well as aging effects in thermoremenant magnetization of antiferromagnetic nanoparticles. The antiferromagnetic nanoparticles show a stronger memory effect than the corresponding effect in the ferromagnetic particles, when the distribution of particles include very small sizes. The situation reverses for bigger sizes. The relaxation of the magnetization after a sudden cooling, heating and removal of fields reiterate the memory effects. We also see a weak signature of size-dependent magnetization fluctuations in aging effect of antiferromagnetic nanoparticles. We find a two-step relaxation of thermoremenant magnetization in antiferromagnetic case, which differs qualitatively from relaxation of ferromagnetic nanoparticles.