Magnetoelastic excitation spectrum in the rare-earth pyrochlore Tb2Ti2O7

Amongst the rare earth pyrochlores, Tb${}_{2}$Ti${}_{2}$O${}_{7}$ remains mysterious: no theory of purely magnetic degrees of freedom can account entirely for its behavior. The discovery of a hybrid magnetoelastic excitation, formed from crystal field and phonon excitations, suggests that spin-lattice coupling may play an important role. Here, the authors use inelastic neutron scattering to make a detailed investigation of the hybrid mode and crystal field excitons that may hold the key to understanding the microscopic interactions of Tb${}_{2}$Ti${}_{2}$O${}_{7}$.