Influence of the interface morphology on the exchange coupling in Fe/Pd/Fe(001) structures

Previous studies of Fe/Pd/Fe trilayers revealed the presence of oscillatory behavior in exchange coupling superimposed on a ferromagnetic background. These structures were characterized by small size terraces (5 nm on a side) at the first Fe/Pd interface. A number of theoretical and experimental stu dies hate shown that the exchange coupling depends on interface quality. Ho wever, systematic studies of this issue have been limited. To study. the in fluence of the interface morphology on exchange coupling we have recently g rown a series of Fc/Pd/Fe trilayers on Fe whisker substrates and on GaAs su bstrates by MBE. These structures exhibit terraces at the first Fe. Pd inte rface ranging in size from 3 to 1000nm. We characterized the quality of our structures by RHEED patterns and RHEED intensity oscillations. We used MOK E and BLS techniques to study the strength of the exchange coupling. Wherea s previous studies Found ferromagnetic coupling for Pd interlayers with thi cknesses on the order of six monolayers, we find significant antiferromagne tic coupling in the samples with smooth interfaces. In contrast, the sample s with rougher interfaces show weak ferromagnetic coupling or no coupling. (C) 1999 Elsevier Science B.V. All rights reserved.