EPR studies of Dy3+ in the singlet-ground-state paramagnets, PrX and TmX (X = P, As, Sb)

The EPR of Dy3+ diluted in singlet-ground-state paramagnets, PrX and TmX (X = P, As) from 5 to 500K was investigated. The g-values at 50K have been found to be 7.1 +- 0.2 and 9 +- 1 for PrAs and TmAs, respectively, and they approach the theoretical g-value for GAMMA6, 6.6, at high temperatures (T approximately equal to 500K). In the temperature range investigated, the observed g-shifts are proportional to the magnetic susceptibilities of the respective hosts. The position of the first-excited state of Dy3+ has been determined by comparing the temperature-dependent intensities of the Dy3+ EPR with those of Gd3+ impurities in the same host. The g-values of Dy3+ in PrP, PrSb, and TmP were also measured at 50K. From the g-shifts at low temperatures the exchange coupling constants between Dy3+ and its surrounding rare-earth ions (Pr3+ and Tm3+) were computed. The temperature variation of the linewidth of Dy3+ in PrAs is discussed