The electronic and magnetic properties of the F-doped CrO2 from first-principles study

• The F-doped CrO2 with low F concentration keeps a high spin polarization.
• The decrease of spin polarization is contributed by the shift of CrIB 3d state.
• The total moment increases about 1 μB by substituting one F atom for one O atom.
• Due to the double-exchange interaction, the magnetic moment is quite diffuse.

The F doping effects on the electronic structure and magnetic properties of CrO2 have been studied using the first principles projector-augmented wave potential within the GGA+U. The F-doped CrO2 with low F concentration keeps a high spin polarization. Due to F doping, five different Jahn–Teller structural distortions are observed for the octahedrons around five groups Cr atoms in F-doped CrO2, this results from the 3d electron orbitals are asymmetrically occupied. Compared with pure CrO2, the decrease of spin polarization of F-doped CrO2 is contributed by the shift of CrIB 3d   state towards low energy region. The impurity moment by substituting F impurities for O atoms are aligned with the host moment and the total magnetic moment increase about 1μB by more substituting one F impurity for one O atom, indicating that magnetic moment can be controlled by F doping. For Cr54O102F6Cr54O102F6, CrIIA and CrIIB alternately arrange in a unbroken F–Cr–F zigzag chain along the 〈111〉〈111〉 direction in the (11¯0) plane, but the additional magnetic moment by substituting F impurity for O does not appear to reside on the Cr ion in the vicinity of the F impurity, but is quite diffuse due to the magnetic double-exchange interaction.