Antiferromagnetic spin ice correlations at (12,12,12) in the ground state of the pyrochlore magnet Tb2Ti2O7

We present high-resolution single-crystal time-of-flight neutron scattering measurements on the candidate quantum spin liquid pyrochlore Tb2Ti2O7 at low temperature and in a magnetic field. At ∼70 mK and in zero field, Tb2Ti2O7 reveals diffuse magnetic elastic scattering at (12,12,12) positions in reciprocal space, consistent with short-range correlated regions based on a two-in, two-out spin ice configuration on a doubled conventional unit cell. This elastic scattering is separated from very low-energy magnetic inelastic scattering by an energy gap of ∼0.06–0.08 meV. The elastic signal disappears under the application of small magnetic fields and upon elevating temperature. Pinch-point–like elastic diffuse scattering is observed near (1,1,1) and (0,0,2) in zero field at ∼70 mK, in agreement with Fennell et al. [Phys. Rev. Lett. 109, 017201 (2012)0031-900710.1103/PhysRevLett.109.017201], supporting the quantum spin ice interpretation of Tb2Ti2O7.