Anomalous pressure dependence of the giant magnetoresistance for Co/Cu magnetic multilayers

The effect of pressure of up to 2.2 GPa on the giant magnetoresistance (GMR) has been investigated for sputtered [Co(10.8 Angstrom)/Cu(t(Cu) Angstrom)](15) magnetic multilayers with various Cu-layer thicknesses, t(Cu). It was found that the MR ratio, Delta rho/rho(s), showing oscillatory hehavior with t(Cu), is strongly affected by the application of pressure at 4.2 K for the samples near the first peak (t(Cu) = 9.8 and 11.7 Angstrom): Delta rho/rho(s) for t(Cu) = 9.8 decreases with increasing pressure, while Delta rho/rho(s) for t(Cu) = 11.7 increases with increasing pressure. On the other hand, the pressure effect on Delta rho/rho(s) for the samples near the second peak (t(Cu) = 21.5 and 23.4 Angstrom) is much smaller than that near the first peak.