K. Tanaka et al., APPLICATION OF CLUSTER VARIATION METHOD TO 3-DIMENSIONAL T-J MODEL, Journal of the Physical Society of Japan, 63(8), 1994, pp. 2909-2918
The square approximation in the cluster variation method is formulated
for the t-J model. By using this approximation, we study the phase tr
ansition to a magnetically ordered state in the three-dimensional t-J
model on a cubic lattice. The Neel order is shown to appear near half-
filled region.