Feature-rich structural, electronic, magnetic and optical properties of the fluorine- and nitrogen-incorporated CaF2 compound

In this work, two new compounds, namely CaF3 and CaF2N, are designed by incorporating fluorine and nitrogen into the CaF2 fluorite structure. The newly created materials show good thermodynamic and structural stability. CaF2 is an insulator with a band gap of 10.92 eV, exhibiting non-magnetic feature. Under the incorporation effects, CaF3 becomes a ferromagnetic half-metallic material with insulator spin-up state with an energy gap of 11 eV and metallic spin-down state. While CaF2N presents the magnetic insulator characteristic with an energy gap of 9.21 and 5.74 eV in the spin-up and spin-down channels, respectively. Consequently, diverse magnetic properties with total spin magnetic moments of 1 mu(B) of CaF3 and 3 mu(B) of CaF2N are obtained, being produced mainly by spin-up state of the incorporated atoms. Interestingly, the population analysis indicates that Ca2+ ion remains its oxidation state in newly created systems. Unusual properties of CaF3 and CaF2N materials provide the possibility of harvesting the visible and far-ultraviolet light with the absorption coefficient reaching values of 30 (10(4)/cm) and 65.6 (10(4)/cm), respectively. Theoretical predictions in this study suggest that the designed materials may be prospective candidates for use in spintronic and optoelectronic devices, applications that have not been done accounting for the pristine CaF2 compound yet.