Perpendicular resistance of Co/Cu multilayers prepared by molecular beam epitaxy

Abstract The magnetoresistance (MR) of layered metal systems with the current in a direction perpendicular to the plane of the layers (CPP) is studied. The technique for measuring the resulting very small resistances utilises a SQUID to act as a high-precision current comparator. The samples are Co/Cu multilayers grown by molecular beam epitaxy (MBE) in ultrahigh vacuum (UHV). Perpendicular resistance measurements are reported for Nb/Cu/X/Cu/Nb where X is the Co/Cu multilayer. The Co is fixed at a nominal value of 1.5 nm while the Cu is varied between 1 and 5 nm. These measurements show large oscillations in the CPP-MR as the Cu thickness in increased. A comparison is made between MBE and sputtered samples.