  Measurements of magnetization, specific heat, electrical resistivity, Hall
effect, and magnetoresistance on single crystalline samples of LaFeAsO grown in
a NaAs flux are reported. While this material is known to be a semimetal, the
temperature dependence of the electrical resistivity data presented herein is
reminiscent of semiconducting behavior and exhibits distinct features
associated with a structural transition and spin density wave (SDW) order.
Magnetoresistance and Hall coefficient measurements were performed in magnetic
fields up to 9 T applied perpendicular to the basal plane using a van der Pauw
configuration. The charge carrier density and mobility indicate that electrons
are the majority charge carriers and exhibit features indicative of the
structural transition and SDW formation. Low temperature X-ray diffraction
measurements have confirmed that the structural transition in these samples
occurs near 140 K, compared to a transition temperature of 156 K observed in
polycrystalline samples. Isotherms of magnetoresistivity measured as a function
of magnetic field can be scaled onto a single curve in which the scaling field
is a linear function of temperature between 2.2 K and 180 K.
