METAMAGNETISM IN PEROVSKITES RMNO3+X (R=GD, TB, DY)

A magnetic study of perovskites RMnO3+x (R = Nd, Eu, Gd, Tb, Dy) is re ported, The compounds NdMnO2.99 and EuMnO2.99 are weak ferromagnets wi th T-N = 88 and 49 K respectively It is shown that GdMnO3 undergoes a transition from antiferromagnetic to weak ferromagnetic state upon coo ling. The antiferromagnetic ordering of the magnetic moments in the Gd sublattice is observed below 6 K. The magnetic moments of TbMnO3.01 a nd DyMnO3.01 are ordered below 7 K. The external field induces an anti ferromagnet-ferromagnet transition in the rare-earth sublattice. The c ritical fields for GdMnO3,TbMnO3.01, and DyMnO3.01 are 5, 10, and 7 kO e, respectively. (C) 1997 American Institute of Physics.