OPTIMIZATION OF GIANT MAGNETORESISTANCE IN ION-BEAM SPUTTERED CO CU MULTILAYERS/

Ion beam sputtering (IBS) was used to prepare Co/Cu multilayer films w ithin the first antiferromagnetic coupling range. Several preparation conditions were varied to optimize the giant magnetoresistance effect. We report the improvement of magnetoresistance by changing the sputte ring gas from Ar to Xe, by finding an optimal substrate position and i on beam acceleration voltage, and by increasing the growth rate. A max imum magnetoresistance of 51% was achieved at room temperature in a st ack with only 16 periods. The obtained improvements compared to previo us efforts are discussed in terms of interface sharpness, layer homoge neity, and impurity incorporation. The main advantage of the establish ed plasma sputtering technique, which still yields somewhat better res ults compared to IBS, appears to he a larger growth rate resulting in less impurity incorporation.