INVESTIGATIONS ON ZN2-XCOXW-TYPE HEXAFERRITE POWDERS AT LOW-TEMPERATURES BY FERROMAGNETIC-RESONANCE

Polycrystalline powder samples of W-type BaZn2-xCoxFe16O27 hexaferrite s are prepared by the glass crystallization method and analyzed by fer romagnetic resonance experiments (FMR) at various temperatures. The in fluence of second-order anisotropy constant in the case of Zn2W and th e determination of K-1 and K-2 in dependence on the temperature is sho wn. FMR spectra are calculated for both a preferential axis and a pref erential plane of magnetization for randomly oriented polycrystalline powder samples. In powders with a specific Co content (x not equal 0), the transition from uniaxial anisotropy at room temperature to planar anisotropy at low temperatures is discussed by way of example on Zn1. 5Co0.5W.