ESR line shape study in the incommensurate phase of K2SeO4and RbH3(SeO3)2crystals

Abstract
The temperature dependence of ESR spectra for K2SeO4 doped with VO2+ and RbH3 (SeO3)2 with Cr3+ has been studied in the incommensurate phases. As already reported in our previous paper, the line shape for K2SeO4 in the temperature range from TI to ≂ TC + 10 K was explained excellently by the plane wave modulation model. On the other hand, in the vicinity of TC the line shape can be quantitatively explained by the spatial modulation including the phase solitons. The experimental line shape for RbH3 (SeO3)2 near TC can be also well expressed by the same model proposed for the incommensurate phase in K2SeO4. This fact indicates that the crystal RbH3(SeO3)2 containing Cr3+ has an incommensurate phase in the temperature range between about 150 and 160 K.