The experimental results show that the exchange coupling field H.. of NiFe/
FeMn for TalNiFe/FeMn/Ta multilayers is higher than that for the spin valve
multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta. The composition and chemical states a
t the surface of Ta(12nm)/NiFe(7nm), Th(12nm)/NiFe(7nm)/Cu(4nm) and Ta(12nm
)/NiFe(7nm)/Cu(3 nm)/NiFe(5 mn) were studied by using x-ray photoelectron s
pectroscopy. The results show that no element from the underlayers Boats ou
t or segregates to the surface for Th(12 nm)/NiFe(7nm), Ta(12 nm)/NiFe(7nm)
/Cu(4 mn). However, Cu atoms segregate to the surface of Ta(12 nm)/NiFe(7nm
)/Cu(3nm)/NiFe(5nm) multilayers, i.e. to the NiFe/FeMn interface for Ta/NiF
e/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at
the interface of NiFe/FeMn is one of the important factors which will cause
the exchange coupling field H.. of Ta/NiFe/FeMn/Ta multilayers to be highe
r than that of Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers.