High frequency magnetic excitations in patterned NiFe∕Cu∕NiFe trilayered stripes subjected to a transverse magnetic field

An experimental and theoretical investigation of the high frequency dynamical properties of trilayered stripes (700nm wide) subjected to an in-plane transverse magnetic field is presented. Stripes were obtained from both asymmetric NiFe(10nm)∕Cu(10nm)∕NiFe(30nm) and symmetric NiFe(30nm)∕Cu(10nm)∕NiFe(30nm) trilayers. Brillouin light scattering from spin waves has been exploited to study the spin mode excitations of these specimens. Several well resolved peaks have been observed in the spectra. These correspond to both localized and quantized spin mode excitations. Their field dependence has been measured as a function of the magnetic field intensity and compared to the theoretical curves, calculated by a micromagnetic numerical model, achieving a good agreement between experiment and theory. In particular, the mode softenings observed at certain values of the external applied field have been related to the cancellation of the static magnetization component along the wire.