Magnetic Excitations of the Kondo Insulator SmB$_{6}$*

Research within the past year indicates the long-studied Kondo insulator SmB$_{6}$ may be a topological insulator, with an insulating bulk at low temperatures and topologically protected metallic surface states. Because electron-electron interactions give rise to the insulating state, there is intense interest in SmB$_{6}$. Using time-of-flight inelastic neutron scattering, we have probed magnetic excitations over a wide range of energy and momentum transfer. Consistent with previous work there is a resonant mode near 14 meV and a broad spectrum of excitations centered near 30 meV. This data set provides a comprehensive map of the Q-dependence of the excitations throughout the Brillouin zone allowing for comparison to theoretical models describing the anomalous insulting state.