Short-range magnetic correlations in quasicrystalline i-Tb-Cd

We report on elastic and inelastic neutron scattering from single-grain isotopically enriched samples to elucidate the local magnetic correlations between Tb3+ moments in quasicrystalline i-Tb-Cd. The inelastic neutron scattering measurements of the crystalline electric field excitations demonstrated that the Tb3+ moments are directed primarily along the local fivefold axes of the Tsai-type cluster as was found for the TbCd6 approximant phase. Based on the inelastic measurements, we consider a simple Ising-type model for the moment configurations on a single Tb3+ icosahedron and enumerate the lowest energy moment configurations. We then calculate the diffuse scattering from these configurations and compare with the experimental magnetic diffuse scattering measurements to identify the most likely single cluster moment configurations and find reasonable agreement between the broad features observed in our scattering simulations. We further use a heuristic glass model as well as large-scale Monte-Carlo simulations of a multicluster model to consider the role of higher-order (longer-range) intercluster correlations for magnetic frustration and the magnetic scattering.