EXCESS MAGNETIZATION OF THE DILUTED ANTIFERROMAGNET MNXMG1-XTIO3 IN LOW FIELDS

The temperature dependence of the excess magnetization Delta M = M-FC - M-ZFC at low fields is examined for the diluted antiferromagnet MnxM g1-xTiO3 with x greater than or equal to 0.62. The Delta M appears at a temperature a little higher than the respective Neel temperature; an d it increases as the temperature decreases. Except the difference of the scale factor, the shape of Delta M vs T curves does not depend on the applied magnetic fields and the magnetic ion concentrations at low fields for the x greater than or equal to 0.64 samples. Moreover, we have firstly found that the temperature dependence of Delta M coincide s with that of the squared sublattice magnetization. The shape of Delt a M vs T curves is also similar to those of the other several diluted antiferromagnets with weak anisotropy reported for the low field regio n. We show that the appearance of Delta M does not originate directly from the random-field effect. The origin of Delta M is discussed.