Magnetic properties of orthoferrites with substitutions in rare-earth sublattice

The effect of partial substitution of Sm3+ ions by Tb2+, Er3+, Dy3+, Gd3+, Tm3+ ions on the behaviour of spontaneous magnetic moment in the temperature range from 4.2 to 400 K is studied. The phase transitions of the Gsub(x)Fsub(z)-Gsub(z)Fsub(x) type have been observed in all the investigated single crystals with Tb3+ ions, including the orthoferrites with Dy3+ ions in the their composition. In the single crystals containing Tb3+ ions at low temperatures a σsub(a)(T) hyperbolic dependence is observed which is indicative of the positive charge of the effective field on the Tb3+ ions. It is established; that while substituting the Sm3+ ions by Er3+ and Tm3+ ones, there are compensation points at 20, 16 and 13.2 K, respectively, in this case the introduction of Tm3+ into the orthoferrite composition produces a shift of Tsub(k) to a higher temperature range than that which could be expected. This points to a rather complicated character of the R-Fe interactions in orthoferrites with different substitutions in rare-earth sublattices