GMR effect of permalloy/Cu multilayers on Si(100) and Si(111)

[Permalloy_1.5nm/Cu(t)]n multilayers with a 5 nm thick Fe buffer layer were sputtered on Si(100) and Si(111). Under the same preparation condition, the giant magnetoresistance (GMR) ratio of the multilayers on Si(100) is always larger than that on Si(111). The GMR ratio is very sensitive to the Ar gas pressure during sputtering. We found that 2 m Torr is the optimum discharge gas pressure. Electrical and magnetic properties of permalloy/Cu multilayers with a Cu layer thickness (t) near its second oscillatory peak were reported. We conclude that the GMR ratio of the [permalloy/Cu(t)]n multilayers was strongly dependent on the Cu layer thickness t, on the periodicity number n, and on the (100) crystalline orientation of the Si substrate.