  We document the coexistence of ferro- and anti-ferromagnetism in pyrochlore
$\rm Yb_2Ti_2O_7$ using three neutron scattering techniques on stoichiometric
crystals: elastic neutron scattering shows a canted ferromagnetic ground state,
neutron scattering shows spin wave excitations from both a ferro-and an
antiferro-magnetic state, and field and temperature dependent small angle
neutron scattering reveals the corresponding anisotropic magnetic domain
structure. High-field $\langle 111 \rangle$ spin wave fits show that $\rm
Yb_2Ti_2O_7$ is extremely close to an antiferromagnetic phase boundary.
Classical Monte Carlo simulations based on the interactions inferrred from high
field spin wave measurements confirm $\psi_2$ antiferromagnetism is metastable
within the FM ground state.
