Temperature-dependent exchange bias properties of polycrystalline PtxCo1-x/CoO bilayers

TL;DR

This study explores how temperature and platinum concentration influence exchange bias in PtxCo1-x/CoO bilayers, revealing that Pt content affects magnetic properties, structural behavior, and the temperature stability of the exchange bias effect.

Contribution

It provides a detailed analysis of how Pt concentration impacts exchange bias, magnetic anisotropy, and interfacial interactions in PtxCo1-x/CoO bilayers, including structural insights from XPS.

Findings

Higher Pt concentration enhances exchange bias.

Non-stoichiometric CoO lowers blocking temperature.

Increased Pt strengthens magnetic anisotropy.

Abstract

Temperature and PtCo composition dependence of exchange bias in PtxCo1-x/CoO bilayers is investigated. It is observed that exchange bias properties, blocking temperature and magnetic anisotropy of the PtxCo1-x/CoO thin films are strongly affected by the concentration of Pt at the common interface. A detailed structural analysis of antiferromagnetic CoO has been done by x-ray photoelectron spectroscopy (XPS). The XPS data revealed that CoO layer grows with non-stoichiometric behavior which results in other cobalt oxide phases and thus lowers blocking temperature for the exchange biased systems. Increase of Pt concentration in PtCo layer strengths the exchange bias and thus decreases training of the system. It also results in enhancement of growth-induced uniaxial magnetic anisotropy and onset of exchange bias at higher temperatures. The role of Pt concentration on the interfacial interactions between ferromagnetic and antiferromagnetic layers, and the effect of superstoichiometric CoO on blocking temperature are also discussed.