LONGITUDINAL RESONANCE IN FERROMAGNETS WITH RANDOM ANISOTROPY - A FORMAL EXPERIMENTAL DEMONSTRATION

Several properties of a new resonance mode are reported. It was detect ed in Co93-xZr7(RE)(x) (RE=Pr, Nd, Dy, Tb) amorphous thin films posses sing an in-plane uniaxial anisotropy H-k. A study as a function of the working frequency shows, that when the external magnetic field H is a pplied in the plane defined by the film normal and H-k the new mode ca n be identified as a longitudinal resonance, which should occur in fer romagnets with random anisotropy, and observed even for H parallel to h(rf)parallel to H-k. The mode is localized and this localization is ' 'stronger'' for higher working frequencies. (C) 1997 American Institut e of Physics.