Oxidation-induced biquadratic coupling in Co/Fe/MgO/Fe(001)

Abstract

We investigate the interlayer exchange coupling in Co/Fe/MgO/Fe(001) via molecular-beam epitaxy synthesis and magneto-optic Kerr effect measurements across wedged samples. By independently varying the oxygen contents of the MgO film and the Fe/MgO interface, the biquadratic coupling is found to be correlated with the interfacial oxidation. Furthermore, the temperature dependence indicates that the biquadratic coupling originates from indirect exchange interactions with magnetic impurities in the MgO spacer.