Ion beam mixing and thermal demixing of Co/Cu multilayers

X-ray reflectivity and magnetotransport studies have been used to probe the effects of ion-beam irradiation and subsequent thermal annealing on the structure and giant magnetoresistance (GMR) in Co/Cu multilayers. Low-dose ion bombardment produces interfacial mixing which is accompanied by a systematic suppression of the antiferromagnetic (AF) coupling and the GMR. For ion doses not exceeding 5 x 10(14) ions/cm(2), subsequent thermal annealing restores the abrupt interlayer structure as well as the GMR. The combination of low-dose ion bombardment and thermal annealing provides an ex situ technique to modify interface structure reversibly over a significant range.