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Fe 3 F 4 with the spinel structure was designed, and its electric and magnetic properties were calculated in system based on density function theories. And then they were compared with those of Fe 3 O 4. From our calculation, Fe 3 F 4 is a kind of new stable approximate half-metal material because its spin-polarization at fermi level is about 95%, which is near to 100%. The steady constant of crystal lattice is 0.643 nm. The energy distance between the top of the up-spin valence band and the fermi level is about 2.05 eV, which is much larger than 0.6 eV of Fe 3 O 4. In the other hand, the resistivity of Fe 3 F 4 is lower than that of Fe 3 O 4. The molecular magnetic moments 10.68μB of Fe 3 F 4 are evidently higher than 4.0μB of Fe 3 O 4. This shows that there is stronger spin-correlation scattering on transmitted carriers in Fe 3 F 4 than in Fe 3 O 4 so that Fe 3 F 4 may have higher magnetoresistance than Fe 3 O 4. Extremely localization of 3d-electrons caused by hybrid orbits of F2p and Fe3d orbits is the mechanism of the distribution of electronic charges and magnetic moments of Fe 3 F 4.

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