Anomaly of ESR Line Width in γ-Irradiated KH₂PO₄ and KD₂PO₄

Abstract

ESR Spectra of γ-irradiated KDP and DKDP were measured. From the temperature dependence of the ESR spectra, it was found that the spectra of γ-irradiated DKDP consisted of three types of spectra and these corresponded to three species of radicals. One of the spectra in γ-irradiated KDP showed anomalous temperature dependence of the line width near the Curie temperature. The anomaly of the line width was explained qualitatively by assuming the presence of the fluctuational motion which critically slowed down near the Curie temperature.