A systematic study of the zinc-blende-type 4d-transition-metal nitrides, which still need to be synthesized, is carried out by means of spin-polarized first-principles full-potential-linearized-augmented-plane- wave calculations using the local spin density approximation. In particular, lattice constants, bulk moduli, band structures and density of states are reported, and trends are discussed.

The utilization of the quantum properties of the electron spin wave function will allow the development of a new class of devices. The problem is still controversial and unsettled, even qualitatively, especially for concentrated spin systems such as 3d metals and their alloys. The variety of crystal structures of 3d metals makes difficult the direct comparison between the experimental results and the theoretical conclusions. On the account of this difficulty, substitutional alloys with the same crystal structure, especially face-centered cubic alloys, have been investigated extensively. In this work the properties of diluted Ga1-xMn xN (x = 0.0630; 0.0315) alloys are calculated in the zinc-blende phase, within the framework of the density functional theory, using the fullpotential linearized augmented plane wave (FLAPW) method and the local density approximation (LDA). The alloys are simulated using 32-atom and 64-atom large unit cells, containing one substitutional Mn atom for a Ga atom. The calculations are spin-polarized and we analyze band structures, density of states and total magnetizations. A half-metallic state is predicted at a0 ~ 4:45Å. The majority-spin band has a rather sharp peak, characteristic of a narrow band, while the minority-spin has a gap. The total magnetization of the cell is 4.00muB which does not change with the Mn concentration. The valence band is ferromagnetically coupled with the Mn atoms, and the spin splitting is not linearly dependent on the Mn concentration.

We report ab-initio all electrons density- functional calculations for the electronic structure of the compounds MnAs and MnN, in the zinc-blende phase. They are potential materials for use in fabrication of new functional semiconductors taking advantage of the spin degree of freedom. The aim is the establishing of the semiconductor spin electronics (spintronics) as a practical technology [H. Ohno, Semiconductor Science and Technology 17, 4 (2002).]. We compare results obtained using the theoretical approaches LDA (Local Density Approximation) and GGA (Generalized Gradient Approximation). The calculations are spin-polarized and we follow the evolution of the band structures as a function of lattice parameter. We compare also the evolution of the density of states of the majority-spins and of the minority-spins. We conclude that, depending on the lattice parameter, both materials may be half-metallic, therefore showing conduction by charge carriers of one spin direction exclusively: the majority- spin band is continuous, while the minority-spin has a gap. Both materials reach a total magnetization of the order of 4 mB. MnN changes from paramagnetic to ferromagnetic with the increase of the lattice parameter.

First-principles calculations of electronic band structures of the ordered cubic alloys Al xGa1-xN and Cd xZn1-xTe are carried out. The band structures are used to provide e ective masses and Luttinger parameters which are useful in the parametrization of theories based on e ective hamiltonians.