RESUMEN
Microstrip ferromagnetic resonance and Brillouin scattering are used to provide a comparative determination of the magnetic parameters of thin permalloy layers interfaced with a non-magnetic (Al(2)O(3)) or with an antiferromagnetic oxide (NiO). It results from our microstructural study that no preferential texture is favoured in the observed polycrystalline sublayers. It is shown that the perpendicular anisotropy can be monitored using an interfacial surface energy term which is practically independent of the nature of the interface. In the interval of thicknesses investigated (5-25 nm) the saturation magnetization does not significantly differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy and exchange bias anisotropy are also derived from the study of the dynamic magnetic excitations and compared with our independent evaluations using conventional magnetometry.
Asunto(s)
Óxido de Aluminio/química , Compuestos Férricos/química , Magnetismo , Modelos Teóricos , Níquel/química , Aleaciones , Modelos MolecularesRESUMEN
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.