Antiferromagnetic Layer Structure Effects on Exchange Coupling Strength in Ion-Beam Deposited Ni80Fe20/Cobalt Oxide Bilayers

概要

論文の詳細を見る
A series of Ni80Fe20/Cobalt oxide bilayers were prepared by a dual ion-beam deposition technique that produced a layer composition that varied from rock-salt CoO ($a=4.27$ Å) to spinel Co3O4 ($a=8.21$ Å) with increasing O2 content in the assist beam. Each polycrystalline layer (${\sim}20$ nm) exhibited a columnar structure perpendicular to the film surface. A strong temperature dependence of coercivity $H_{\text{c}}$ and exchange bias field $H_{\text{ex}}$ was found in these Ni80Fe20/cobalt oxide bilayers. At $T=10$ K, films prepared with 34% O2 in the assist beam exhibited an exchange shift $H_{\text{ex}}\sim -200$ Oe that persisted at temperatures higher than 30 K. The variations in $H_{\text{c}}$ and $H_{\text{ex}}$ as a function of %O2 are related to the interfacial roughness and magnetic state of CoO or Co3O4. The transition temperature of Co3O4 has increased above the bulk value via exchange coupling with the permalloy.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-06-15