LOW-FIELD REMANENT MAGNETIZATION IN SITE-DILUTED EASY-AXIS ANTIFERROMAGNETS - A UNIVERSAL BEHAVIOR

The magnetization of the systems, K2Fe1-xInxCl5.H2O, Rb(2)Fe(1-x)ln(x) Cl-5.H2O and Mn1-xZnxF2, is studied in low magnetic fields applied alo ng the easy axis (H-axial < 10 Oe). A remanent magnetization M(r) alwa ys appears below the Neel temperature T-N when cooling in a fixed axia l field H-axial > 10(-3) Oe. M(r) increases with decreasing T. At a fi xed T, M(r) increases with H-axial, but M(r) is practically saturated in fields as low as similar to 1 Oe. The normalized remanent magnetiza tion is a universal function of the reduced temperature t = T/T-N. Thi s function is: 1) independent of H-axial for a given sample, 2) indepe ndent of x for a given system, and 3) the same for the three site-dilu ted systems. The effective critical exponent beta(r), which describes the T-dependence of M(r), is between 0.35 and 0.4.