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

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=B_b+C₁Є+C₂Є² rather than a first-order one of B₂=B_b+C₁Є provides a better fit for the observed behavior of B₂ versus film strain, Є, where B_b is the bulk value. The relationship between B₂ and Є observed in the present study reveals that the second-order correction is crucial for understanding the dependence of B₂ on Є in an ultrathin regime. © 2001 American Institute of Physics.