Pressure-Dependent Magnetization Studies of Two Rare Earth-Based Intermetallic Systems*

Pressure dependent magnetization studies have been performed on two rare earth-based ternary intermetallic systems, R$_{2}$CoIn$_{8}$, where R=Gd, Dy and Pr, and Pr$_{6}$Ni$_{2}$Si$_{3}$, the n=2 member of the Pr$_{(n+1)(n+2)}$Ni$_{n(n+1)+2}$Si$_{n(n+1)}$ family. The pressure dependence of the magnetization was measured for 2$<$T$<$300 K, 0$<$H$<$ 9 T and hydrostatic pressures 0$\le $P$\le $8 kbar using a vibrating sample magnetometer. For the R$_{2}$CoIn$_{8}$ system, R=Dy and Gd order antiferromagnetically at T$_{N}$=17.0 and 34.5 K, respectively and dT$_{N}$/dP=+0.1 K/kbar for R=Dy and +0.4 K/kbar for R=Gd. Pr$_{2}$CoIn$_{8}$ is a van Vleck paramagnet, indicating a crystalline electric field (CEF) singlet ground state. For Pr$_{6}$Ni$_{2}$Si$_{3}$, the Curie temperature (T$_{C}$= 35.0 K) and the saturation magnetization (1.35 $\mu _{B}$/Pr) decrease non-linearly with increasing pressure, consistent with a pressure-induced increase in the CEF splitting. The Pr$^{3+}$ ground state is presumably a singlet, as the local Pr symmetry is very low. Preliminary high field VSM data suggest that a CEF level crossing occurs at 10.5 T where magnetization increases sharply to above 3.0 $\mu _{B}$/Pr.