  Dirac semimetals have attracted a great deal of current interest due to their
potential applications in topological quantum computing, low-energy electronic
applications, and single photon detection in the microwave frequency range.
Herein are results from analyzing the low magnetic (B) field
weak-antilocalization behaviors in a Dirac semimetal $Cd_{3}As_{2}$ thin flake
device. At high temperatures, the phase coherence length $l_{\phi}$ first
increases with decreasing temperature (T) and follows a power law dependence of
$l_{\phi}\propto$ T$^{-0.4}$. Below ~ 3K, $l_{\phi}$ tends to saturate to a
value of ~ 180 nm. Another fitting parameter $\alpha$, which is associated with
independence transport channels, displays a logarithmic temperature dependence
for T > 3K, but also tends to saturate below ~ 3K. The saturation value, ~
1.45, is very close to 1.5, indicating three independent electron transport
channels, which we interpret as due to decoupling of both the top and bottom
surfaces as well as the bulk. This result, to our knowledge, provides first
evidence that the surfaces and bulk states can become decoupled in electronic
transport in Dirac semimetal $Cd_{3}As_{2}$.
