Study On Half-Heusler And Huesler Half-Metallic Magnetic Materials

Half-metallic magnetic(HMM) materials have high Cure temperature and 100% spin polarization.So they have significant application potential in the spin-electronics field. In practical application, instability of HMM led to decrease of the spin polarization.Therefore,we need to discover new HMM with more steady properties.First-principle is used to investigate the Heusler compounds Cr2TiX (X=Al, Ga, Si, Ge, Sn, Sb),Cr2VX(X= Ga, Si, Ge, Sb) and Co2YBi,and half-Heusler compounds CoYBi (Y=Mn, Cr). We study the electronic structures and magnetic properties and predict their physical characteristics.We also perform some synthesis experiments and tests.The electronic,magnetic and bonding properties of Heusler alloys Cr2TiX (X=Al, Ga, Si, Ge, Sn,Sb) which contain two low-valence transition metals atoms Cr and Ti, have been studied. The results show that Cr2TiSb exhibits half-metallicity at equilibrium state with 100% spin polarization. In addition, Cr2TiGa and Cr2TiSn exhibit nearly half-metallicity.First-principle is used to investigate the Heusler compounds Cr2VX (X= Ga, Si, Ge, Sb). The results show that Cr2VSb exhibits half-metallic and Cr2VSi and Cr2VGe exhibit nearly half-metallic. Their band structures show a striking difference between the majority and minority spin directions.We have studied the electronic structures and magnetic properties of Heusler phase Co2YBi and half-Heusler phase CoYBi (Y=Mn, Cr). Co2MnBi and Co2CrBi are predicted to be half-metallic magnetic materials with magnetic moment of 6μB and 5μB repectively, well consistent with the Slater-pauling rule.