First-Principles Study On The Electronic Structures, Magnetism, And Half-Metallicity Of Full-Heusler Mn₂YP（Y=Ti, V, Cr, Fe, Co, Ni, Cu, Zn）Alloys

The discovery of giant magnetoresistance effect (GMR) is a milestone in the development of Spintronics. The Nobel Prize in Physics2007goes to Fert and Grunberg professors for their discovery of the GMR. In the information transmission, processing and storage, spintronics devices not only use the electronic charge but also use the electron’s freedom of spin degree, so it has excellent characteristics, such as low power consumption, nonvolatile, high integration density and so on. At present, the spin polarization rate is very low when the electrons are injected into the semiconductors from the ferromagnetic materials, which is one of the main problems in the spintronics. Because the half-metallic material has100%spin polarization, so it is considered to be the ideal source of spin injection, and has important applications in the spintronics.The electronic structures, magnetic properties and half-metallic properties of the full-Heusler Mn2YP (Y=Ti, V, Cr, Fe, Co, Ni, Cu, Zn) alloys are investigated by using the full potential linearized augmented plane wave (FLAPW) method which is based on the density functional theory (DFT), and adopted the generalized gradient approximation (GGA) for the exchange-correlation energy. For the Mn2YP (Y=Ti, V, Cr) alloys, we considered the Cu2MnAl-type ordered structure, whereas the Mn2YP (Y=Fe, Co, Ni, Cu, Zn) alloys have the Hg2CuTi-type ordered structure. We optimized the lattice constants of the alloys by the total energy variations with the lattice constants. The calculated results show that(1) The optimized lattice constants of Mn2YP (Y=Ti, V, Cr) alloys with the Cu2MnAl-type ordered structure are5.670A,5.545A,5.570A, and the total spin magnetic moments are-0.135μB,1.029μB,0μB, respectively. The Mn2TiP and the Mn2CrP alloys are conventional ferromagnetic materials, while the Mn2VP alloy is non magnetic material.(2) The optimized lattice constants of Mn2YP (Y=Fe, Co, Ni, Cu, Zn) alloys with the Hg2CuTi-type ordered structure are5.552A,5.578A,5.633A,5.722A,5.804A, and the total spin magnetic moment are3.000μB,4.000μB,4.239μB,1.987μB,2.640μB, respectively. We found that the Mn2FeP and Mn2CoP alloys have the half-metallic character; the widths of the band gap in the spin down band are0.176eV and0.427eV, respectively. The total spin magnetic moments are in good agreement with the Slater-Pauling rule:Mt=Zt-24. The Mn2CuP alloy is a nearly half-metallic material, and has the band gap,0.133eV, in the spin down band, and the total spin magnetic moment is close to the2μB, which is in good agreement with the Slater-Pauling rule:Mt=Zt-28. On the other hand, the Mn2NiP and the Mn2ZnP alloys are conventional ferromagnetic materials.