Magnetoelastic coupling in thin films with weak out-of-plane anisotropy

Direct measurements of the magnetoelastic (ME) stresses in a Cu/Ni(200nm)/Cu/Si(001) epitaxial film are reported. The ME coefficient B-gamma,B-2=B-1 has been determined as a function of the applied magnetic field (+/-15 kOe) and the temperature (300-10 K). The coefficient B-gamma,B-2(T) decreases slightly with the temperature as the square of the reduced magnetization m(2), and its value at 0 K is extrapolated to be 8.7 MPa. The ME stress measured along equivalent <100> in-plane directions shows a strong dependence on the applied magnetic field, while the transversal stress is close to zero at all field strengths, which means there is essentially no transverse magnetostrictive deformation, and that the longitudinal stress takes almost the entire value of B-gamma,B-2, which indicates deformation along the field direction. This observation can be explained in terms of the stripe magnetic domain structure present in this thick nickel film.