Magnetoresistance of Fe3O4/Au/Fe3O4 and Fe3O4/Au/Fe spin-valve structures

Abstract A detailed study of the in-plane magnetotransport properties of spin valves with one and two Fe 3 O 4 electrodes is presented. Fe 3 O 4 /Au/Fe 3 O 4 spin valves exhibit a clear anisotropic magnetoresistance in small magnetic fields but no giant magnetoresistance (GMR). The absence of GMR in these structures is due to simultaneous magnetization reversal in the two Fe 3 O 4 layers. By contrast, a negative GMR effect is measured on Fe 3 O 4 /Au/Fe spin valves. The negative GMR is attributed to an electron spin scattering asymmetry at the Fe 3 O 4 /Au interface or an induced spin scattering asymmetry in the Au interfacial layers.