Giant magnetoresistance of artificial NiFe/Cu, NiCo/Cu and CoFe/Cu superlattices and their temperature dependence

The dependence of the magnetoresistance (MR) ratio on the composition of the magnetic layers and the temperature (between 4.2 and 300 K) was studied systematically for FeNi/Cu, NiCoCu and CoFe/Cu multilayers. The MR ratio exhibits a maximum near Co, which is in qualitative agreement with the theoretical calculation made by Inoue and coworkers (J. Magn. Magn. Mater., 104–107 (1992) 1883; 136 (1994) L33). The dependence of the MR ratio on the temperature is well explained by the theoretical calculation proposed by Hasegawa (Phys. Rev. B, 47 (1993) 15 073, 15 080).