Relationship between granularity of antiferromagnet and exchange bias

TL;DR

This study investigates how doping antiferromagnetic CoO with platinum affects exchange bias in multilayer films, revealing that increased granularity enhances uncompensated spins but reduces magnetic stability, with effects varying by film type and temperature.

Contribution

It provides new insights into how doping-induced granularity influences exchange bias and magnetic stability in antiferromagnetic multilayers.

Findings

Exchange bias increases with Pt doping in epitaxial films.

In polycrystalline films, exchange bias remains unchanged at low temperature and decreases at higher temperatures.

Granularity enhances uncompensated spins but reduces magnetic stability of antiferromagnetic grains.

Abstract

We studied exchange bias in magnetic multilayers incorporating antiferromagent CoO doped with up to 35 atomic percent of Pt. The exchange bias increased with doping in epitaxial films, but did not significantly change in polycrystalline films at the lowest measured temperature of 5 K, and decreased at higher temperatures. We explain our results by the increased granularity of the doped antiferromagnetic films, resulting in simultaneous enhancement of the uncompensated spin density and reduction of the magnetic stability of antiferromagnetic grains.