Low temperature magnetic properties of Nd₂Ru₂O₇

Abstract

We present magnetic susceptibility, heat capacity, and neutron diffraction measurements of polycrystalline Nd₂Ru₂O₇ down to 0.4 K. Three anomalies in the magnetic susceptibility measurements at 146, 21 and 1.8 K are associated with an antiferromagnetic ordering of the Ru⁴⁺ moments, a weak ferromagnetic signal attributed to a canting of the Ru⁴⁺ and Nd³⁺ moments, and a long-range-ordering of the Nd³⁺ moments, respectively. The long-range order of the Nd³⁺ moments was observed in all the measurements, indicating that the ground state of the compound is not a spin glass. The magnetic entropy of Rln2 accumulated up to 5 K, suggests the Nd³⁺ has a doublet ground state. Lattice distortions accompany the transitions, as revealed by neutron diffraction measurements, and in agreement with earlier synchrotron x-ray studies. The magnetic moment of the Nd³⁺ ion at 0.4 K is estimated to be 1.54(2)µ _B and the magnetic structure is all-in all-out as determined by our neutron diffraction measurements.