  Two-dimensional Dirac semimetals with a single massless Dirac cone exhibit
the parity anomaly. Usually, such a kind of anomalous topological semimetallic
phase in real materials is unstable where any amount of disorder can drive it
into a diffusive metal and destroy the half-integer quantized Hall conductivity
as an indicator of parity anomaly. Here, based on low-energy effective model,
we propose an anisotropic Dirac semimetal which explicitly breaks time-reversal
symmetry and carries a half-integer quantized Hall conductivity. This
topological semimetallic phase can be realized on a deformed honeycomb lattice
subjected to a magnetic flux. Moreover, we perceptively investigate the
disorder correction to the Hall conductivity. The results show that the effects
of disorder can be strongly suppressed and thereby the nearly half-integer
quantization of Hall conductivity can exist in a wide region of disorder,
indicating that our proposed anisotropic Dirac semimetal is an exciting
platform to investigate the parity anomaly phenomena.
