Evidence of decoupling of surface and bulk states in Dirac semimetal CdAs.

Dirac semimetals have attracted a great deal of current interests due to their potential applications in topological quantum computing, low-energy electronic devices, and single photon detection in the microwave frequency range. Herein are results from analyzing the low magnetic () field weak-antilocalization behaviors in a Dirac semimetal CdAsthin flake device. At high temperatures, the phase coherence lengthfirst increases with decreasing temperature () and follows a power law dependence of∝. Below ∼3 K,tends to saturate to a value of ∼180 nm. Another fitting parameter, which is associated with independent transport channels, displays a logarithmic temperature dependence for > 3 K, but also tends to saturate below ∼3 K. 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 CdAs.