摘要
Single-crystal Co(1120)/Cr(100) superlattices (SLs) have been successfully grown on MgO (100) and Al O (1102) substrates with 100 Å Mo as buffer layers by molecular beam epitaxy (MBE). Excellent epitaxial growth was evidenced by reflection high-energy electron diffraction (RHEED). Magneto-resistance (MR) measurements have been performed using a conventional four-point technique. We have observed negative MR (NMR ≈ 4.8%) for [Co(40 Å)/Cr(5 Å)] SLs, giant positive MR (PMR ≈ 30%) for [Co(5 )/Cr(5 Å)] SLs. It is likely that the NMR effect is introduced by the Co/Cr SL while PMR is induced by the Mo buffer layers. Interestingly, PMR samples show a distinct roughness effect compared to NMR samples. Systematically we have found that NMR increases with increasing interfacial roughness, while PMR samples show the opposite behavior.