Abstract
In this work, detailed electronic structure calculations of alkali metal fluorides A(2)MnF(6) (A = K, Rb, Cs) have been performed using ab-initio calculating techniques based on density functional theory (DFT). We applied different exchange correlation functionals, namely Wu-Cohen generalized gradient approximation (WC-GGA), modified Becke Johnson potential (mBJ) and GGA plus Hubbard U method in order to treat the exchange correlation energy. The calculated lattice constants are found in excellent agreement with earlier experimental results. The electronic band structure and density of states show that Cs2MnF6 is half metallic, exhibiting semiconductivity in spin up direction and metallic behavior in spin down direction. The compounds, K2MnF6 and Rb2MnF6, are predicted as wide bandgap materials. The DFT+U method gives quite accurate results of the electronic bandgap as compared with other approximations. The states Mn-3d and F-2p contribute largely to the conduction and valence energy bands. Additionally, magnetic calculations reveal strong ferromagnetic nature of these compounds. The half-metallic nature along with ferromagnetism make Cs2MnF6 a promising candidate for future applications in spintronics. Furthermore, the wide bandgap observed in K2MnF6 and Rb2MnF6 indicate their utility for light-emitting diodes (LEDs) transparent lenses and optical coatings.