Abstract

The frustrated pyrochlore magnet Yb2Ti2O7 has been proposed as a candidate ””quantum spin ice” material. Here we report extensive inelastic neutron scattering measurements of the spin dynamics and complementary specific heat measurements to map the phase diagram in magnetic field applied along the cubic [001] direction *, not explored experimentally in detail before. The high quality of our single crystals is evidenced by a sharp zero-field anomaly near 220 mK. We characterize how the spin excitations evolve gradually from very high applied magnetic fields (9 T) when one-magnon excitations dominate, all the way down to zero field where the spectrum is replaced by a scattering continuum extended over a broad energy range. Through fits of the dispersion relations at high field we propose a re-evaluation of the spin Hamiltonian to consistently explain all existing spin dynamics data for different field directions and propose a phenomenological model of the evolution of the spin dynamics in applied field.

• J. D. Thompson, P. McClarty, D. Prabhakaran, I. Cabrera, T. Guidi and R. Coldea, (in preparation)