Microcrystalline β-RbNd(MoO4)2: spin polarizing DFT+U

Abstract

Using density functional theory plus the Hubbard Hamiltonian (U), we have investigated the spin up (↑) and spin down (↓) electronic band structure, density of states, electronic charge density distribution and dispersion of the optical properties of microcrystalline β-RbNd(MoO₄)₂. We have applied U on the 4f orbital of Nd atoms and 4d orbital of Mo atoms. The calculated electronic band structure indicates that β-RbNd(MoO₄)₂ is a direct band gap semiconductor with a spin up (↑) energy gap which is lower than that of the spin down (↓). This is attributed to the different location of Nd-f in the spin up (↑) than the spin down (↓) case. The total valence charge density distribution in the (1 0 0) and (1 0 1) crystallographic planes for spin up (↑) and spin down (↓) were analyzed. The calculated bond distances show good agreement with the measured ones. The optical properties were investigated to seek deep insight into the electronic structure. It was found that the β-RbNd(MoO₄)₂ crystal exhibits negative uniaxial anisotropy and shows a lossless region and considerable anisotropy.