Field Induced Order and Spin Waves in the Pyrochlore Antiferromagnet   Tb2Ti2O7
  High resolution time-of-flight neutron scattering measurements on Tb2Ti2O7 reveal a rich low temperature phase diagram in the presence of a magnetic field applied along [110]. In zero field at T=0.4 K, terbium titanate is a highly correlated cooperative paramagnet with disordered spins residing on a pyrochlore lattice of corner-sharing tetrahedra. Application of a small field condenses much of the magnetic diffuse scattering, characteristic of the disordered spins, into a new Bragg peak characteristic of a polarized paramagnet. At higher fields, a magnetically ordered phase is induced, which supports spin wave excitations indicative of continuous, rather than Ising-like spin degrees of freedom. 
K.C. Rule, J.P.C. Ruff, B.D. Gaulin, S.R. Dunsiger, J.S. Gardner, J.P.   Clancy, M.J. Lewis, H.A. Dabkowska, I Mirebeau, P. ...