Probing the Magnetic Polarizations of Delocalized Electrons in Exchange-coupled Co/CuNi Multilayers by X-ray Magnetic Circular Dichroism Measurements

Abstract

Magnetic polarizations of delocalized electrons in spacer layers are detected in exchange-coupled Co/CuNi multilayers by a measurement of X-ray magnetic circular dichroic absorptions. The size of the Cu K-edge dichroism shows a variation closely related to the oscillatory exchange coupling as a function of the spacer CuNi thickness. The magnetic polarization of the CuNi 4p electrons is locally minimal at the spacer thickness where the magnetoresistance reaches a local maximum, indicating that the integrated local spin density in the spacer layer oscillates with the spacer thickness with the same period as, but in 180° phase with, the indirect coupling of the Co moments across the CuNi layer.