  A number of rare-earth monopnictides have topologically non-trivial band
structures together with magnetism and strong electronic correlations. In order
to examine whether the antiferromagnetic (AFM) semimetal YbAs ($T\rm_N$ = 0.5
K) exhibits such a scenario, we have grown high-quality single crystals using a
flux method, and characterized the magnetic properties and electronic structure
using specific heat, magnetotransport and angle-resolved photoemission
spectroscopy (ARPES) measurements, together with density functional theory
(DFT) calculations. Both ARPES and DFT calculations find no evidence for band
inversions in YbAs, indicating a topologically trivial electronic structure.
From low-temperature magnetotransport measurements, we map the
field-temperature phase diagram, where we find the presence of a field
stabilized phase distinct from the AFM phase at low temperatures. An extremely
large magnetoresistance (XMR) for both YbAs and the nonmagnetic counterpart
LuAs, is also observed, which can consistently be accounted for by the presence
of electron-hole compensation. Moreover, an angle-dependent study of the
Shubnikov-de Haas effect oscillations reveals very similar Fermi surfaces
between YbAs and LuAs, with light effective masses down to at least 0.5 K,
indicating that the Yb-$4f$ electrons are well localized, and do not contribute
to the Fermi surface. However, the influence of the localized Yb-$4f$ electrons
on the magnetotransport of YbAs can be discerned from the distinct temperature
dependence of the XMR compared to that of LuAs, which we attribute to the
influence of short-ranged spin correlations that appear well above $T\rm_N$.
