Reversal behavior of exchange-biased submicron dots

TL;DR

This study investigates how the size of nanostructured Fe dots on FeF2 affects magnetic reversal behavior, revealing vortex states and exchange bias variations through experiments and simulations.

Contribution

It provides new insights into size-dependent magnetic reversal and vortex formation in exchange-biased nanostructures, supported by experimental and simulation data.

Findings

Vortex states observed in 300 nm Fe dots.

Exchange bias field decreases in smaller dots.

Micromagnetic simulations align qualitatively with experiments.

Abstract

Nanostructured Fe dots were prepared on antiferromagnetic FeF2 thin films and investigated by magneto-optical Kerr effect (MOKE). We studied the influence of dot sizes on the magnetic hysteresis and compared the result with both continuous thin film bilayers and nanostructured Fe/FeF2 pillars. Hysteresis loops were measured at temperatures below and above (10 and 90 K, respectively) the Neel temperature of the antiferromagnet. A vortex state is found for dots of 300 nm diameter, where the exchange bias field is reduced compared to larger dot system and the continuous bilayer. Micromagnetic simulations including the interaction with the antiferromagnet show qualitatively similar behavior.