Antiferromagnetism of LnRhO sub(3) (Ln = rare earth)

The crystallographic and magnetic properties of perovskite-type rhodite LnRhO sub(3) (Ln = rare-earth ions except Ce and Pm) were studied. LnRhO sub(3) (Ln = La, Eu, Lu) shows paramagnetism with very small susceptibility, suggesting that the Rh super(3+) ion has no magnetic moment. LnRhO sub(3) (Ln = Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb) shows antiferromagnetic transition at temperatures between 0.5 and 3.5 K; however, no transition was observed for LnRhO sub(3) (Ln = Pr, Tm) down to 0.5 K. The effective moment k sub(eff) agrees with the theoretical moment of free rare-earth ions, indicating the dominant magnetic contribution of rare-earth ions. The Weiss temperature [theta] has a strong correlation with the spin value of rare-earth ions, suggesting that the superexchange interaction is a dominant interaction in LnRhO sub(3). The magnetization of antiferromagnetic samples tends to be saturated above 20-30 kOe, but the moments at 70 kOe are far from the theoretical moments. Antiferromagnetic samples seem to have an intermediate state and require a more intense magnetic field to attain saturation.