Calculation of giant magnetoresistance in Fe/Cr/Fe and Co/Cr/Co sandwiches

The giant magnetoresistance (GMR) vs. interfacial roughness in sandwich structures of Fe/Cr/Fe and Co/Cr/Co is calculated numerically by using the recursive formula for the DC conductivity under the condition of the perfect specular scattering at surfaces. Small magnetoresistances of 3.6 and -1.9% are obtained for Fe/Cr/Fe and Co/Cr/Co, respectively, even in the case of no interfacial roughness, because of the difference in effective masses of electrons under the potential fields of respective magnetic configurations in the sandwich structure. The spin-dependent interfacial scattering due to interfacial roughness is the major contribution to the GMR, which is more remarkable for Fe/Cr/Fe than for Co/Cr/Co because of the fact that the energy levels of minority spin electrons at Fe and Co atomic sites are equal to and lower, to some extent, than the one at the Cr atomic site, respectively. It is found that the most favorable probability of atomic mixing at interfaces is 30-40% for both sandwiches