Collective magnetic excitations of Ho3+ ions in grain-aligned HoBa2Cu3Ox (x=7, 6.2)

Abstract

Inelastic neutron scattering (INS) has been used to study the magnetic excitations of Ho3+ ions in grain-aligned samples of HoBa2Cu3Ox in both orthorhombic (x approximately=7) and tetragonal (x approximately=6.2) phases. The magnetic excitations associated with the lowest ground state crystalline electric field transition exhibit dispersion in the (a,b) plane but remain constant in energy along the c axis. The data are analysed in the random-phase approximation in terms of a generalized Heisenberg model including anisotropies in the coupling of the spin operators.