Magnetic excitations in Ho2Co17and Ho2Fe17

Abstract

The low-energy part (2Co₁₇ and Ho₂Fe₁₇ were found to consist of three modes: (i) a highly dispersive transition-metal mode; (ii) a non-dispersive local mode and (iii) a weakly dispersive mode degenerate with the local mode at the zone boundary. These modes are interpreted within the linear spin wave formalism, using a two-sublattice approximation for the magnetic structure, and taking isotropic exchange and single-ion crystal-field interactions into account. The exchange constants, the anisotropy of the transition-metal sublattice and two linear combinations of the rare-earth crystal-field parameters B₂⁰, B₄⁰, B₆⁰ and B₆⁶ are determined by fitting the linear spin wave solution to the observed dispersion relations.