A quasi two dimensional metallic state of CaHCl driven by La doping studied from first principles theory

Abstract

The present study reports the electronic, optical, vibrational properties and doping studies of the alkaline earth hydride-halides (MHX, M = Ca, Sr, Ba and X = Cl, Br, I) for the first time using density functional theory calculations. The structural optimization and vibrational properties are calculated using the plane-wave pseudopotential method, and the electronic and optical properties are carried out using the full potential linearized augmented plane wave method. Ground state electronic structure properties ensure these compounds to be direct bandgap insulators except for CaHI, which is an indirect bandgap material with the bandgap ranging from 2.3 to 4.0 eV. Our analysis mainly highlight two aspects: (i) optical isotropy in the studied compounds in lower energy region though they are structurally anisotropic, (ii) quasi two dimensional Fermi surfaces driven by insulator to metal transition by La doping in CaHCl (CaHCl: La) along with anisotropic nature of the electrical conductivity, leading to device applications.