NUCLEAR ANTIFERROMAGNETIC ORDERING IN PRBE13

Tile nuclear magnetic susceptibility of the Van Vleck paramagnet PrBe1 3 has been measured at temperatures below 20 mK. In zero field we obse rve an antiferromagnetic Curie-Weiss behavior with a Weiss temperature - = -2.2 mK and a Neel ordering temperature of T-N = 0.4 mK. We have considered a mean-field model incorporating nearest-neighbor (nn) and next-nearest-neighbor (nnn) exchange interactions on a simple cubic la ttice to describe the Pr nuclear moments. The results of the calculati on suggest a type II ordered magnetic structure.