Electronic Structures of New Half-Metal Material CrFe2O4

Geometric structures of cubic spinel materials (CrxFe1-x)(A)(CryFe2-y)(B)O-4 were optimized and their magnetic and electric properties were calculated using the first principles. Electronic structures and the micromechanism of half-metallicity of CrFe2O4 were analyzed based on coordinate field theory. From our calculation, it is showed that (CrxFe1-x)(A)(CryFe2-y)(B)O-4, has half-metallicity only when x=1.0 and y=0.0. CrFe2O4 is a type of ferrimagnetic IIB-type half-metal material and its molecular magnetic moments are about 5.6 mu(B) which is higher than the 4-0 mu(B) of Fe3O4. Electronic structures of Cr-ions can be approximately written as Cr(+)t(2g)(1)(sic)t(2g)(3)(sic) and those of Fe-ions can be approximately Fe(2+)t(2g)(3)(sic)e(g)(2)(sic)t(2g)(1). The micromechanism of the half-metallicity of CrFe2O4 is concerned with the strong covalent written as interaction in the coordinate compounds ML4 and ML6. Mixed orbits between central ions and their ligand result in separated up-Spin sub-bands and the Fermi level lies in the gaps of up-spin sub-bands.