Evidence of decoupling of surface and bulk states in Dirac semimetal $Cd_{3}As_{2}$

TL;DR

This study provides the first evidence that surface and bulk electronic states can become decoupled in the Dirac semimetal $Cd_{3}As_{2}$, revealing distinct transport channels at low temperatures.

Contribution

It demonstrates the decoupling of surface and bulk states in $Cd_{3}As_{2}$ through analysis of weak-antilocalization behaviors and phase coherence length.

Findings

Surface and bulk states are decoupled below ~3K.

Three independent transport channels are identified.

Surface-bulk decoupling is evidenced by saturation of parameters.

Abstract

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 $Cd_{3}As_{2}$.