Spin glass transition in a thin-film NiO/Permalloy bilayer

TL;DR

This paper investigates the spin glass transition in a NiO/Permalloy bilayer, revealing temperature-dependent aging behaviors and magnetic history effects that support the existence of a spin glass transition at the exchange bias blocking temperature.

Contribution

It provides experimental evidence for a spin glass transition in a thin-film NiO/Permalloy bilayer, highlighting the temperature-dependent aging and magnetic history effects.

Findings

Aging characteristics are temperature-independent below the blocking temperature.

Behavior changes rapidly above the blocking temperature.

Magnetic history effects qualitatively change across the transition.

Abstract

We experimentally study magnetization aging in a thin-film NiO/Permalloy bilayer. Aging characteristics are nearly independent of temperature below the exchange bias blocking temperature, but rapidly vary above it. The dependence on the magnetic history qualitatively changes across this temperature. The observed behaviors are consistent with the spin glass transition at the exchange bias blocking temperature, with significant implications for magnetism and magnetoelectronic phenomena in antiferromagnet/ferromagnet bilayers.