  Recently, Yb-based triangular lattice antiferromagnets have garnered
significant interest as possible quantum spin liquid candidates. One example is
YbMgGaO4, which showed many promising spin liquid features, but also possesses
a high degree of disorder owing to site-mixing between the non-magnetic
cations. To further elucidate the role of chemical disorder and to explore the
phase diagram of these materials in applied field, we present neutron
scattering and sensitive magnetometry measurements of the closely related
compound, YbZnGaO4. Our results suggest a difference in magnetic anisotropy
between the two compounds, and we use key observations of the magnetic phase
crossover to motivate an exploration of the field- and exchange
parameter-dependent phase diagram, providing an expanded view of the available
magnetic states in applied field. This enriched map of the phase space serves
as a basis to restrict the values of parameters describing the magnetic
Hamiltonian with broad application to recently discovered related materials.
