EXCHANGE COUPLING BETWEEN IRON LAYERS SEPARATED BY BCC COPPER

The exchange coupling between Fe layers separated by bce Cu is calcula ted for Fe/Cu/Fe (001) trilayers. It is shown that the coupling is bas ically regulated by three extrema of the bulk bcc Cu Fermi surface. Th e contributions from those extrema are all of the same order of magnit ude, but that associated with the ''belly'' at the Gamma point dominat es. The calculated temperature dependence of the coupling varies consi derably with spacer layer thickness. Individually, the amplitudes of t hese extrema contributions decrease with temperature, each according t o a different rate. Such an effect may cause an actual increase of cou pling with temperature for some Cu thicknesses.