In situ magnetoelastic coupling and stress-evolution studies of epitaxial Co35Pd65 alloy films in the monolayer regime

Abstract

We report in situ measurements of magnetoelastic coupling, B2, and stress, σ, in Co35Pd65 alloy films epitaxially grown on a Cu/Si(001) substrate in a thickness range of 1–10 ML by means of a highly sensitive optical deflection-detecting system. It was found that the value of B2 increases from 0.72×107 J/m3 at 2 ML to 3.31×107 J/m3 at 10 ML. A second-order strain correction of B2=Bb+C1ε+C2ε2 rather than a first-order one of B2=Bb+C1ε provides a better fit for the observed behavior of B2 versus film strain, ε, where Bb is the bulk value. The relationship between B2 and ε observed in the present study reveals that the second-order correction is crucial for understanding the dependence of B2 on ε in an ultrathin regime.