Observation of stress relaxation via step formation in Co/Pt metallic superlattices

Abstract

We report the direct observation of stress relaxation in lattice-mismatched Co/Pt superlattices with increasing Co-layer thickness, via in situ and real-time measurements using a submonolayer-sensitive stress measurement apparatus. A large tensile stress in the Co layers found to be relaxed when the Co layer thickness was larger than 2 monolayers, corresponding to the critical thickness expected for coherent-to-incoherent transition in this system. Cross-sectional high-resolution transmission electron microscopy studies revealed that stress relaxation was realized by formation of steps, rather than misfit dislocations, near the interfaces.