First-principle Calculation on the Magnetic and Electric Properties of New Half-metal Fe_2LaO_4

New rare-earth half-metal Fe2LaO4 is designed, and then is geometrically optimized with the first-principle pseudo-potentials based on the density functional theories. The magnetic and electric properties including the charge order and the molecular magnetic moments of Fe2LaO4 are calculated in system. Then the electronic structures of Fe2LaO4 are analyzed from coordinate field theories. From our calculation, Fe2LaO4 is a new rare-earth ferromagnetic ⅡB-type half-metal. For Fe2LaO4, the stable lattice constant is about 0.623 nm and the molecular magnetic moment is about 1.0μB. The mechanism of soft magnetism of Fe2LaO4 is that La has more outermost electrons than Fe so that the crystal field of the coordinate compounds ML4 and ML6 of Fe2LaO4 is very strong. The average electronic structures of ML4 and ML6 can be approximatively written as a1g1↑a1g1↓t1u3↑t1u3↓eg2↑eg2↓t2g3↑t2g3↓ and a1g1↑a1g1↓t1u3↑t1u3↓t2g3↑t2g3↓eg2↑eg2↓eg1↑, respectively.