INFLUENCE OF CRYSTAL-STRUCTURE ON THE MAGNETORESISTANCE OF CO/CR MULTILAYERS

Epitaxial Co/Cr multilayers, and single-crystal Co thin films etc. have been grown on MgO and Al2O3 substrates with Cr and Mo as buffer layers by molecular beam epitaxy technique. From the structure and magnetoresistance studies, we have found that the ferromagnetic anisotropy of resistance (AMR) is strongly influenced by the buffer layer, but with negligible effect due to the variation of the structure of Co films. The AMR of Co film on Cr buffer layer is quite small (0.1%); however, the MR of Co/Cr multilayers is almost one order larger than the AMR of Co film on Cr buffer layer. An enhancement factor of 4 for the MR in Co/Cr multilayers by the interface roughness has been observed. This suggests that the effect due to the spin dependent scattering at the interfacial regions of the superlattice is larger than that due to the spin dependent scattering in the ferromagnetic layers for the MR in the Co/Cr multilayer system.