Antiferromagnetism of LnRhO3 (Ln = rare earth)

The crystallographic and magnetic properties of perovskite-type rhodite LnRhO3 (Ln = rare-earth ions except Ce and Pm) were studied. LnRhO3 (Ln = La, Eu, Lu) shows paramagnetism with very small susceptibility, suggesting that the Rh3+ ion has no magnetic moment. LnRhO3 (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 LnRhO3 (Ln = Pr, Tm) down to 0.5 K. The effective moment μeff agrees with the theoretical moment of free rare-earth ions, indicating the dominant magnetic contribution of rare-earth ions. The Weiss temperature Θ has a strong correlation with the spin value of rare-earth ions, suggesting that the superexchange interaction is a dominant interaction in LnRhO3. 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.

Research highlights▶ The asymptotic Curie temperature has a strong correlation with the spin value of rare-earth ions suggesting the existence of a exchange interaction between rare-earth ions. ▶ The magnetic moments of heavy rare-earth ions at 7 T are one-half of the saturation moment suggesting the existence of metamagnetic transition at higher magnetic field.