Comparison of atomic structure anisotropy between Co-Pd alloys and Co/Pd multilayer films

We have employed Co K-edge extended x-ray absorption fine structure measurements with linear polarization dependence to investigate the chemical short-range order (SRO) and interatomic distance anisotropy in CoXPd_1-X alloy $(X=0.16,0.31)$ and [Co(2 )/Pd(Y )]₁₃ multilayer films $(Y=15,$ 32). The SRO parameters of in-plane first nearest neighbors, 0.063--0.068 in the alloys and 0.012--0.036 in the multilayers, are observed. Surprisingly, these counterintuitive results show clear evidence that the Co atoms at the Co/Pd interfaces in multilayers have more alloylike characteristic than those in alloys with respect to local chemical environment.