Magnetic and crystal-field properties of the magnetic superconductor DyNi2B2C from 161Dy Moessbauer spectroscopy

We have utilized the 161Dy Moessbauer effect to investigate the magnetic properties and the nature of the ground state of the DyNi2B2C quaternary magnetic superconductor (TN∼11 K, Tc∼6 K). Detailed analysis of the spectra suggests that the magnetic transition is of first order and the Dy moments of 9.8μB at saturation are confined in the basal plane. Isomer shift in this material (∼0.5 mm/s) is significantly less than that observed in metallic Dy which implies charge transfer from 6s orbitals of Dy onto the strongly bonded C atoms. The second-order B02 crystal-field parameter is positive and estimated to amount to about 2 K. The ground-state crystal-field doublet is composed primarily of the |±1/2 right-angle component of the J=15/2 free ion term. Higher-order crystal-field terms should be included in the exchange crystal-field Hamiltonian for a detailed account of the experimental results. copyright 1996 The American Physical Society