Magnetic interactions in (Pr, La)3RuO7 and Pr3(Ru, Nb)O7

Abstract

Abstract The rare-earth ruthenate Pr3RuO7 is a Mott insulator displaying magnetic ordering at two temperatures T N1 = 36 K and T N2 = 55 K. By substituting diamagnetic La for Pr and diamagnetic Nb for Ru, T N1 is shown to be associated with ordering among the rare earths and T N2 among the Ru cations. These results are similar to those of Sm3RuO7, but the ordering temperatures for Pr3RuC7 are large compared with all other known Ln3MO7 systems and there is less divergence between field-cooled and zero-field-cooled magnetic susceptibility for T < T N2. Isothermal magnetization measurements, including pulsed-field measurements, show hysteretic-field-induced transitions at B ≈ 4T for T ≪ TN1 associated with a spin reorientation of the Pr moments. Further characterization of Pr3RuO7 is provided from measurements of the heat capacity for 2K < T < 17 K and electrical resistivity for 100K < T < 300 K.