Spin liquid correlations, anisotropic exchange, and symmetry breaking in Tb2Ti2O7

We have studied the low-energy spin dynamics between 4.6 and 0.07 K in a Tb2Ti2O7 single-crystal sample by means of inelastic neutron scattering experiments. The spectra consist in a dual response, with a static and an inelastic contribution, showing striking Q dependencies. We propose an interpretation involving an anisotropic exchange interaction in combination with a breaking of the threefold symmetry at the rare earth site. Simulations of the Q-dependent scattering in the random phase approximation account well for the inelastic response.