Studies On The Electronic Structure And Magnetism Of Half-metallic Ferromagnets

The information carrier of traditional electronic components such as diode and audion, is electronic charge, but the electronic spin is not considered. In recent years, studies on the semiconductor spintronics indicate that the diluted magnetic semiconductors can be used to manage and store information by means of the electronic charge and spin. However, nowadays, the key to semiconductor spintronics is that the efficiency of spin-polarized electrons injected into semiconductors is very low, one needs to find some magnetic materials with high spin-polarization. Half-metallic ferromagnet has a higher Curie temperature and almost 100% spin-polarization. Therefore, it will become the perfect spin injection fountain to semiconductor. With the development of science and technology, the capability of computers becomes more and more advanced, which makes it possible to design new functional materials by the computer simulations. In this paper, our purpose is to predict new half-metallic ferromagnets by the computer simulations. With the help of the plane-wave pseudopotential (PWPP) method based on the density functional theory (DFT), we investigated the electronic structure and the magnetism of the binary CrS and CrP as well as the transition metal(V, Cr, Mn and so on) doped zincblende semiconductor CdTe. For the binary CrS, our computational results indicate that the spin-up(majority spin) electrons of zincblende CrS are metallic while there is an obvious energy gap around the Fermi level. This character remains in the variation range of -3%―20% of lattice constant. Moreover, the magnetic moment per formula unit of zincblende CrS is 4.000 μB. Therefore, we can predict that zincblende CrS is a relatively steady half-metallic ferromagnet. The calculations of CrP indicate that the zincblende CrP is half-metallic ferromagnetic, but the half-metallic ferromagnetism disappears when its lattice constant is compressed. So the zincblende CrP is a quasi half-metallic ferromagnet. The calculations of the electronic structure and the magnetism of the transition metal V-, Cr-, Mn-, Fe-, Co-and Ni-doped zincblende semiconductor CdTe indicate that only the Cd_0.5V_0.5Te and Cd_0.5Cr_0.5Te are half-metallic ferromagnets. Their magnetic moments per supercell are 3.000 μB and 4.000 μB respectively. The half-metallic ferromagnetism originates from the d-d exchange and p-d hybridization.