THE EFFECT OF MAGNETIC-ORDERING ON THE CRYSTAL-FIELD LEVELS OF ERNI2B2C

The quaternary compound ErNi2B2C becomes superconducting with a critic al temperature of 9 K. DC magnetisation indicates the presence of magn etic ordering of the Er moments at approximate to 7 K. Specific heat m easurements show a Schottky anomaly around 45 K with a magnitude of 10 J mol K-1 which agrees well with our model for the crystal-field sche me and neutron scattering data. We observed changes in the widths and positions of peaks in the crystal-field spectra, indicating the build up of magnetic interactions with the f electrons and thus contributing to the crystal-held Hamiltonian.