Highly anisotropic Dirac fermion and spin transport properties in Cu-graphane

Abstract

Inspired by the successful synthesis of hHv-graphane [Nano Lett. 15 903 (2015)], a new two-dimensional (2D) Janus material Cu-graphane is proposed based on the first-principles calculations. Without the spin–orbit coupling (SOC) effect, Cu-graphane is a Dirac semimetal with a highly anisotropic Dirac cone, whose Fermi velocity ranges from 0.12 × 105 m/s to 2.9 × 105 m/s. The Dirac cone near the Fermi level can be well described with an extended 2D Dirac model Hamiltonian. In the presence of the SOC effect, band splitting is observed around the Fermi level, and a large intrinsic spin Hall conductivity (ISHC) with a maximum value of 346 (ℏ/e) S/cm is predicted. Moreover, the spin Hall transport can be regulated by slightly adjusting the Fermi energy, e.g., grid voltage or chemical doping. Our work not only proposes a new 2D Janus material with a highly anisotropic Dirac cone and a large ISHC, but also reveals that a large ISHC may exist in some Dirac systems.