Dependence of the dielectric function and electronic properties on the Co layer thickness in giant-magnetoresistance Co/Au multilayers

A series of Co/Au multilayers, which exhibit (111) texture and low-field gi ant magnetoresistance (GMR), were examined with spectroscopic ellipsometry (SE) in a range of Co layer thicknesses (t(Co)) The obtained optical dielec tric functions show a systematic variation with increasing t(Co). Analysis of the optical transitions reveals nonmonotonic variations in plasma freque ncy omega(p) and the interband parameters with increasing t(Co). These anom alies in the electronic states reflect drastic changes in Co layering above 1.5 nm of t(Co) The complementary study of SE and GMR measurements, on sim ilar Co/Cu and Co/Au multilayers with (111) texture, provide experimental e vidence that an interplay between spin-dependent interface and bulk scatter ing contributions can explain the observed linear decrease of GMR with incr easing t(Co). [S0163-1829(99)06341-9].