Superspin glass aging behavior in textured and nontextured frozen ferrofluid

TL;DR

This study investigates how magnetic anisotropy-axis alignment affects aging behavior in superspin glasses of frozen ferrofluids, revealing different aging dynamics in textured versus non-textured states.

Contribution

It demonstrates the impact of nanoparticle magnetic anisotropy alignment on aging behavior, showing different scaling exponents in textured and non-textured superspin glass states.

Findings

Scaling exponent fected by anisotropy alignment

Textured and non-textured states exhibit different aging dynamics

Magnetic anisotropy influences superspin glass relaxation behavior

Abstract

The effect of magnetic anisotropy-axis alignment of individual nanoparticles on the collective aging behavior in the superspin glass state of a frozen ferrofluid has been investigated. The ferrofluid studied here consists of maghemite nanoparticles (\gamma-Fe2O3, mean diameter = 8.6 nm) dispersed in glycerin at a volume fraction of ~15%. The low temperature aging behavior has been explored through 'zero-field cooled magnetization' (ZFCM) relaxation measurements using SQUID magnetometry. The ZFCM response functions were found to scale with effective age of the system in both textured and non-textured superspin glass states, but with markedly different scaling exponents, \mu. The value of {\mu} was found to shift from ~0.9 in non-textured case to ~ 0.6 in the textured case, despite the identical cooling protocol used in both experiments.