Magnetic correlations in the intermetallic antiferromagnet Nd₃Co₄Sn₁₃

Abstract

Specific heat, magnetic susceptibility, and neutron scattering have been used to investigate the nature of the spin system in the antiferromagnet NdCoSn. At room temperature NdCoSn has a cubic, Pm-3n structure similar to YbRhSn. Antiferromagnetic interactions between, Nd ions dominate the magnetic character of this sample and at 2.4 K the Nd spins enter a long range order state with a magnetic propagation vector q = (0 0 0) with an ordered moment of 1.78(2) µ at 1.5 K. The magnetic Bragg intensity grows very slowly below 1 K, reaching ~2.4 µ at 350 mK. The average magnetic Nd configuration corresponds to the 3D irreducible representation Γ. This magnetic structure can be viewed as three sublattices of antiferromagnetic spin chains coupled with each other in the 120°-configuration. A well-defined magnetic excitation was measured around the 1 1 1 zone centre and the resulting dispersion curve is appropriate for an antiferromagnet with a gap of 0.20(1) meV.