Spin wave modelling in arrays of ferromagnetic thin stripes: application to Brillouin light scattering in permalloy

The magnetic Brillouin scattering of arrays of permalloy stripes with rectangular 29 nm × L cross section (L = 500, 1000, 1500 nm) is studied versus the amplitude and the direction of the applied magnetic field and of the transferred wavevector. A simple model provides a satisfactory agreement of the full set of experimental results: each stripe is viewed as a continuous film showing an in-plane anisotropy due to the demagnetizing effects induced by lateral surfaces. We introduce an anisotropy field H(a) = aM, where M stands for the magnetization and where the coefficient a can be evaluated directly, at least approximately. In addition, we give an account of the previously studied magnetic mode quantization and of the observed variations in the Stokes/anti-Stokes asymmetry in patterned arrays as well as in continuous films.