NMR-STUDIES OF CO-59 IN CU CO/CU(111) TRILAYER SYSTEMS GROWN BY MBE/

NMR using the Co-59 nucleus has been measured for a series of Cu/Co/Cu (111) trilayers grown by MBE with Co thicknesses ranging from 25 to 17 8 Angstrom. The Co layer retains the Cu fee structure up to a thicknes s of similar to 60 Angstrom at which point the hcp structure is favour ed. This structural transition is not identical for each sample sugges ting that the point at which the transition occurs depends on the exac t growth conditions including the thickness of the Cu underlayer. Our results suggest that for very thin (15 Angstrom) Cu underlayers the tr ansition to hcp occurs at thicknesses less than 60 Angstrom.