Nonoscillatory magnetoresistance in Co/Cu/Co layered structures with oscillatory coupling

Using sputtered thin-film layered structures comprising Si/[8×(20- Ru/x Cu)] /(30-) Co/tCu Cu/30- Co /(150- Fe50Mn50) with x=8 and 12, we demonstrate that the oscillation in the coupling of the two Co layers as the Cu-layer thickness, tCu, is varied, is not accompanied by an oscillation in the amplitude of the magnetoresistance. Thus the previously reported oscillation in magnetoresistance in Fe/Cr, Co/Ru, Co/Cr, and Co/Cu multilayers is not a fundamental electronic effect but a consequence of the inability to vary consistently the angles between the magnetizations of these multilayers. © 1991 The American Physical Society.