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 178 Angstrom. The Co layer retains the Cu fee structure up to a thickness of similar to 60 Angstrom at which point the hcp structure is favoured. This structural transition is not identical for each sample suggesting that the point at which the transition occurs depends on the exact growth conditions including the thickness of the Cu underlayer. Our results suggest that for very thin (15 Angstrom) Cu underlayers the transition to hcp occurs at thicknesses less than 60 Angstrom.