Electronic structure and elastic properties of Au/Cr(001) superlattices.

We present a first-principles calculation of the electronic structure and elastic properties of a series of Au/Cr(001) superlattices with modulation wavelengths between 30 and 60 \AA{}. The electronic-structure calculations are performed with the linear muffin-tin-orbital method in the atomic-sphere approximation. Results for the density of states and the charge transfer at the interfaces as a function of the modulation wavelength are presented. The force theorem has been used in the investigation of the elastic behavior of the system. We have performed a detailed analysis of the variation of the band contribution to the shear elastic constant ${\mathit{c}}_{44}$, with particular reference to the Fermi-surface contribution. This analysis allows us to investigate the role of the electronic-structure variations induced by layering in the elastic anomalies experimentally observed in metallic superlattices. We show that the origin of the enhancement of the ${\mathit{c}}_{44}$ elastic constant observed in Au/Cr at small modulation wavelengths cannot be ascribed to a Fermi-surface Brillouin-zone interaction mechanism.