Magnetic neutron scattering from quasicrystalline Zn–Mg–Ho and Zn–Mg–Y at low temperatures

In contrast to the magnetic transition metal ions in other quasiperiodic alloys, the RE (RE=rare earth) ions in icosahedral Zn–Mg–RE show localised magnetic moments due to localised 4f electrons. Long range as well as short range order of these moments are still under discussion. To investigate the magnetic properties of these fci-structures of Frank–Kasper type, we performed inelastic neutron scattering experiments at temperatures between 1.6 and 25.0 K and measured the DC magnetic susceptibility. The results show mainly paramagnetic scattering of the samples. Comparison with the data of Zn–Mg–Y ensures, that the observed scattering is not of phononic or phasonic nature. The lineshape of the quasielastic peak can be modeled by a shifted Lorentzian. The observed shift is small (approximately 0.6 meV) and shows no dispersion. The linewidth is constant in Q and increases with temperature. A possible interpretation of this behaviour is the existence of a crystal field splitting.