Abstract
Random-field effects have been studied in the two-dimensional dilute antiferromagnets Rb2CocMg1-cF4 (c=0.8, 0.7 and 0.6), using static susceptibility under a uniform magnetic field H0. The author found that in dilute systems the static susceptibility diverges at the Neel temperature, which originates from the coupling between uniform and staggered fluctuations. It is remarkable that the H0-induced rounding of the transition peaks was observed, consistent with the destruction of the phase transition under random magnetic fields.