Dirac half-metallicity of Thin PdCl(3) Nanosheets: Investigation of the Effects of External Fields, Surface Adsorption and Defect Engineering on the Electronic and Magnetic Properties

PdCl(3) belongs to a novel class of Dirac materials with Dirac spin-gapless semiconducting characteristics. In this paper based, on first-principles calculations, we have systematically investigated the effect of adatom adsorption, vacancy defects, electric field, strain, edge states and layer thickness on the electronic and magnetic properties of PdCl(3) (palladium trichloride). Our results show that when spin-orbital coupling is included, PdCl(3) exhibits the quantum anomalous Hall effect with a non-trivial band gap of 24 meV. With increasing number of layers, from monolayer to bulk, a transition occurs from a Dirac half-metal to a ferromagnetic metal. On application of a perpendicular electrical field to bilayer PdCl(3), we find that the energy band gap decreases with increasing field. Uniaxial and biaxial strain, significantly modifies the electronic structure depending on the strain type and magnitude. Adsorption of adatom and topological defects have a dramatic effect on the electronic and magnetic properties of PdCl(3). In particular, the structure can become a metal (Na), half-metal (Be, Ca, Al, Ti, V, Cr, Fe and Cu with, respective, 0.72, 9.71, 7.14, 6.90, 9.71, 4.33 and 9.5 μ(B) magnetic moments), ferromagnetic-metal (Sc, Mn and Co with 4.55, 7.93 and 2.0 μ(B)), spin-glass semiconductor (Mg, Ni with 3.30 and 8.63 μ(B)), and dilute-magnetic semiconductor (Li, K and Zn with 9.0, 9.0 and 5.80 μ(B) magnetic moment, respectively). Single Pd and double Pd + Cl vacancies in PdCl(3) display dilute-magnetic semiconductor characteristics, while with a single Cl vacancy, the material becomes a half-metal. The calculated optical properties of PdCl(3) suggest it could be a good candidate for microelectronic and optoelectronics devices.