  We report the synthesis and basic properties of single crystals of a new
binary compound, Yb$_{3}$Pt$_{4}$. The Yb ions in this compound are fully
trivalent, and heat capacity measurements show that the crystal field scheme
involves a doublet ground state, well separated from the excited states, which
are fully occupied above $\sim$ 150 K. The heat capacity displays a large,
weakly first order anomaly at 2.4 K, where a cusp is observed in the magnetic
susceptibility signalling the onset of antiferromagnetic order. The entropy
associated with this order is the full Rln2 of the doublet ground state,
however the magnetic susceptibility in the ordered phase is dominated by a
large and temperature independent component below the Neel temperature. The
heat capacity in the ordered state originates with ferromagnetic spin waves,
giving evidence for the inherently local moment character of the ordered state.
The electrical resistivity is unusually large, and becomes quadratic in
temperature exactly at the Neel temperature. The absence of analogous Fermi
liquid behavior in the heat capacity and the magnetic susceptibility implies
that Yb$_{3}$Pt$_{4}$ is a low electron density system, where the Fermi surface
is further gapped by the onset of magnetic order.
