Magnetic order in the double pyrochlore Tb2Ru2O7

Abstract

Polycrystalline Tb2Ru2O7 has been studied using dc susceptibility, specific heat and neutron scattering techniques. The high temperature paramagnetic state is dominated by the single ion character of Tb3 + and very similar to that of the well-studied spin liquid Tb2Ti2O7. However, both the Ru4 + and Tb3 + sublattices order, at about 110?K and 3.5?K, respectively. Although the Tb sublattice does not fully order until 3.5?K, it is polarized in the presence of the internal field generated by the Ru4 + sublattice and possesses a significant moment at 7?K. Magnetic entropy measurements suggest that four levels exist in the first 30?K and inelastic neutron scattering investigations revealed two more levels at 10 and 14?meV. As the magnetic sublattices order, the excitations are perturbed from that measured in the paramagnetic state. These data are compared to data for other terbium based and double pyrochlores.