SPIN-WAVE THEORY OF MAGNETIC-ORDERING IN UNI4B

We study properties of UNi4B using the Heisenberg model. Considering t he spin operators as classical vectors, we show that the classical gro und state of this model is the vortexlike U spin arrangement in the ba sal plain. By means of the spin-wave method we calculate the temperatu re dependence of the specific heat at low temperatures, and estimate t he coupling constants. From the obtained coupling constants we get the transition temperature T-N = 8.7 K.