COMPARATIVE-STUDY OF GIANT MAGNETORESISTANCE IN COZR CU AND CO/CU MULTILAYERS/

Since amorphous Co100-xZrx alloys present ultrasoft properties, higher sensitivity is expected in CoZr/Cu multilayers compared to the Co/Cu system as investigated in the present work from two types (I and II) o f hybrid magnetic structures [(F-1/F-2/F-1)Cu](15) where (F-1/F-2/F-1) is a magnetic sandwich corresponding to either [(CoZr/Co/CoZr)](15) ( type I) or [(Co/CoZr/Co)Cu](15) (type II) and F-1 is a very thin magne tic layer inserted at the interfaces between the Cu layer and the magn etic F-2-based multilayers. Strong changes in the magnetization hyster esis curve, the indirect exchange coupling J and the magnetoresistive properties are observed with the insertion of a very thin magnetic CoZ r (Go) layer at thr interfaces between Cu spacer layers and the magnet ic Co (CoZr) layer in Co/Cu (CoZr/Cu) multilayers. Insertion of a 2 An gstrom thick CoZr layer into interfaces of the Co/Cu type I multilayer s induces significant reduction by a factor 5 of J and the magnetoresi stance Delta R/R. Opposite evolution is observed when a thin Co layer is inserted in CoZr/Cu type II multilayers. The dependences of the mag netic and magnetoresistive characteristics with the insertion are corr elated with the interface roughness change as deduced from XRD at low angles.