  Dirac semimetals (DSMs), which host Dirac fermions and represent new state of
quantum matter, have been studied intensively in condensed matter physics. The
exploration of new materials with topological states is im- portant in both
physics and materials science. In this article, we report the synthesis and the
transport properties of high quality single crystals of YbMnSb$_2$. YbMnSb$_2$
is a new compound with metallic behavior. Quantum oscillations, including
Shubnikov-de Haas (SdH) oscillation and de Haas-van Alphen (dHvA) type
oscillation, have been observed at low temperature and high magnetic field.
Small effective masses and nontrivial Berry phase are extracted from the
analyses of quantum oscillations, which provide the transport evidence for the
possible existence of Dirac fermions in YbMnSb$_2$. The measurements of
angular-dependent interlayer magnetoresistance (MR) indicate the interlayer
transport is coherent. The Fermi surface (FS) of YbMnSb$_2$ possesses quasi-two
dimensional (2D) characteristic as determined by the angular dependence of SdH
oscillation frequency. These findings suggest that YbMnSb$_2$ is a new
candidate of topological Dirac semimetal.
