MBE GROWTH AND FMR, BLS AND MOKE STUDIES OF EXCHANGE COUPLING IN FE WHISKER/CR/FE(001) AND IN FE/CU/FE(001) LOOSE SPIN STRUCTURES

The exchange coupling has been studied in structures which consist of two ferromagnetic layers separated by non-ferromagnetic spacers (trilayers), The exchange coupling was measured using FMR and BLS techniques in the temperature range 77-400 K. Two systems were investigated: (a) Fe whisker/Cr/Fe(001) and (b) Fe/Cr/Fe(001), The oscillatory thickness dependence of the exchange coupling through a spin-density wave Cr spacer will be discussed and compared with recent data obtained by other groups, Cu interlayers were deposited either in a pure form, or a single monolayer of Cu/Fe alloy ('loose spins') was inserted between two pure bcc Cu(001) layers. Several such 'loose spin' structures were engineered to test the behavior of 'loose spin' structures, It was found that the presence of Fe impurity atoms has a strong tendency to decrease the direct bilinear exchange coupling, The contribution of 'loose spins' to the exchange coupling can be made significant, and even dominant, by a suitable choice of the RKKY coupling energy between the 'loose spins' and the surrounding ferromagnetic layers.