The q-state Potts model in a random field with a discrete distribution of statistically independent fields ordered along any of the q states is studied in mean-field theory. Detailed phase diagrams are obtained in a two-component order-parameter theory for q = 3 and a one-component theory for general q. Lines of criticai and tricritical points are found in the first case and lines of criticai points in the second one, in the presence of a sufficiently large, constant uniform field.
Physical review. B, Condensed matter. New York. Vol. 39, no. 10-b (Apr. 1989), p. 7132-7139