Long-range order and lattice mismatch in metallic superlattices

Abstract

A general diffraction relation for crystalline-crystalline superlattices, including random interfacial disorder of a Gaussian type induced by the lattice mismatch between the constituents, is derived and applied to superlattices composed of materials with large symmetry and lattice-parameter difference. The interfacial disorder caused by an important lattice mismatch is found to be responsible for the reduced long-range order at large scattering vector observed in many superlattices. Moreover, the increase of the interfacial disorder with lattice mismatch and modulation wavelength shows the importance of misfit dislocations in addition to interfacial roughness.