FERROMAGNETIC-RESONANCE AND NONLINEAR ABSORPTION IN P-NPNN

Ferromagnetic Resonance (FMR) study has been reported in beta-phase p- NPNN(nitrophenyl nitronyl nitroxide) with Tc=0.6K. We have observed no n-linear line shapes at the lowest temperatures. The line shape is rel ated to the effect known as the ''foldover effect''[1]. We confirmed t hat the temperature dependent g-value so far reported can be understoo d by the demagnetization effect using spherically shaped samples. An i ntrinsically anisotropic g-values are observed depending on the applie d field directions. This is due to the anisotropy field along the crys tal b-axis.