films with low carrier density

Cd₃As₂ is a typical three-dimensional topological Dirac semimetal, characterized by a pair of Dirac points protected by rotational symmetry. While high-crystallinity and high-flatness Cd₃As₂ films have been obtained by the combination of pulsed laser deposition and subsequent high-temperature annealing [1,2], the carrier density is rather high compared to ones prepared by molecular beam epitaxy [3,4]. In this talk, we report quantum transport properties of Cd₃As₂ thin films epitaxially grown by molecular beam epitaxy. A typical film thicker than 100 nm shows a carrier density of 5×10¹⁶ cm^-3 and an electron mobility exceeding 3×10⁴ cm²/Vs. In this thickness regime corresponding to the three-dimensional electronic structure, the film shows plateau-like structures in the Hall resistance, indicating the emergence of a two-dimensional conduction state. This can be understood to originate from the Weyl orbit surface state of the topological Dirac semimetal.

[1] M. Uchida et al., Nat. Commun. 8, 2274 (2017).
[2] Y. Nakazawa et al., Sci. Rep. 8, 2244 (2018).
[3] Y. Liu et al., NPG Asia Mater. 7, e221 (2015).
[4] T. Schumann et al., APL Mater. 4, 126110 (2016).