Giant magnetoresistance in CO/CU, CO9FE/CU, and CO7.5FE2.5/CU multilayers

We report That giant. magnetoresistance(MR) at room temperature up to 52% for low field change of 0.9kOe can be attained in (Co9Fe/Cu)nmultilayers. A set of (CoxFel-x/Cu)nmultilayers (x=1.0, 0.9 and 0.75) was prepared by an ion beam sputter deposition method on MgO(110) single crystal substrates. The MR ratio was found to be quite sensitive to the argon acceleration voltage(Vg) in ion beam sputtering and have a maximum around Va=600V. In the preparation condition for obtaining maximum MR ratio, strong antiferromagnetic coupling(J) for the CoxFei-xlayers via thin cu layers and the oscillation behavior for this indirect exchange coupling with a 12A period were observed. We found that the MR ratio for CoxFe 1-x multilayers is larger than that for co/cu multilayers in the higher Co-concentration range in the CoxFe1-xalloy. We also found that in-plane uniaxial anisotropy(Ku), on the order of 106erg/cc, was induced when this system was prepared on MgO(110). Giant MR can be induced for a small external field change for film with the magnetocrystalline anisotropy. MR curves behavior can be explained by metamagnetic transition when Ku, J and Zeeman terms are considered.