Exchange bias in laterally oxidized Au/Co/Au nanopillars

TL;DR

This paper investigates how lateral oxidation in Au/Co/Au nanopillars induces exchange bias and enhances coercivity, with experimental and simulation analysis revealing the microscopic origin related to core/shell structures.

Contribution

It introduces a novel understanding of exchange bias in nanopillars caused by lateral oxidation and provides a combined experimental and Monte Carlo simulation approach.

Findings

Exchange bias appears due to lateral oxidation of Co interlayer.

The exchange bias field depends on nanopillar size and oxidation degree.

Monte Carlo simulations clarify the microscopic core/shell origin.

Abstract

Au/Co/Au nanopillars fabricated by colloidal lithography of continuous trilayers exhibit and enhanced coercive field and the appearance of an exchange bias field with respect to the continuous layers. This is attributed to the lateral oxidation of the Co interlayer that appears upon disc fabrication. The dependence of the exchange bias field on the Co nanodots size and on the oxidation degree is analyzed and its microscopic origin clarified by means of Monte Carlo simulations based on a model of a cylindrical dot with lateral core/shell structure.