A study of the anti-ferromagnetic quadrupolar ordering in Dy ¹¹B₂C₂ through inelastic neutron scattering

Inelastic neutron scattering measurements have been carried out to investigate the crystal field (CF) excitations of DyB2C2 in order to understand the mechanisms of the quadrupolar ordering (TQ) observed at 24.7 K. Our analysis shows that the ground state is made up of nearly degenerate two Kramer doublets forming a 'quasi-quartet' ground state. This is consistent with heat capacity measurements, which have shown an estimated entropy of ∼Rln2 at TN (15.3 K) and an additional ∼Rln2 at TQ. A considerable shift and change in the width of the CF excitations and the splitting of the quasi-quartet ground state into two well-resolved doublets below TQ as well as a Zeeman splitting below TN have also been observed.