An experimental and theoretical investigation of structural and electronic properties of hexagonal BiCoO3 thin film grown using pulsed laser deposition technique

A new multiferroic hexagonal BiCoO₃ (h-BCO) isotypic to hexagonal YMnO₃ thin film is successfully grown using Pulsed Laser deposition (PLD) technique for the first time. The h-BCO structure is confirmed with the Rietveld refinement. The refined lattice parameters are estimated to be a = b = 6.0956 Å and c = 11.3583 Å, α = 90°, β = 90°, γ = 120° having P6₃cm space group. Experimentally h-BCO thin film is found to exhibit a direct band gap of 3.20 eV and possess room temperature multiferroicity having. In order to further analyze the experimental work in the present study, the structural, magnetic, electronic and optical properties of h-BCO have been investigated using first-principles calculation. A-type AFM is found to be most stable magnetic state and indirect band gap of 2.80 eV is observed using DFT. Further, the optical properties along [100], [010] and [001] direction are predicted using DFT and it has been observed that the optical properties along [001] direction are different from other two directions thus confirming the anisotropy in the material. The theoretical investigations can be used as reference for experimental work and can provide important insight for future applications of h-BCO.