Metamagnetic Transitions and Stepwise GMR in Uniaxial Fe/Cr Superlattices

We investigated the structure, magnetic and magnetoresistive properties of antiferromagnetically coupled [Fe(85A)/Cr(tCr)]12 superlattices with the Cr layers thickness tCr = 12.4 and 13.6 A, grown simultaneously on (100)MgO and (211)MgO substrates. It is shown that the (211)MgO substrate is appropriate for the growth of (210)Fe/Cr multilayers with a strong uniaxial in-plane anisotropy. The stepwise behavior of magnetization and magnetoresistance is revealed in the case when the magnetic field is applied along the easy axis in a film plane of (211)MgO/[(210)Fe/Cr]12 superlattices. The steps on M(H) and ΔR(H)/R dependences are caused by the flip of the magnetic moments of individual Fe layers. The qualitative information about the sequence of spin-flip transitions is extracted from the comparative analysis of magnetization and magnetoresistance data.