23 research outputs found
Ab-initio calculation of the effective on-site Coulomb interaction parameters for half-metallic magnets
Correlation effects play an important role in the electronic structure of
half-metallic (HM) magnets. In particular, they give rise to non-quasiparticle
states above (or below) the Fermi energy at finite temperatures that reduce the
spin polarization and, as a consequence, the efficiency of spintronics devices.
Employing the constrained random-phase approximation (cRPA) within the
full-potential linearized augmented-plane-wave (FLAPW) method using maximally
localized Wannier functions, we calculate the strength of the effective on-site
Coulomb interaction (Hubbard and Hund exchange ) between localized
electrons in different classes of HM magnets considering: (i)
\emph{sp}-electron ferromagnets in rock-salt structure, (ii) zincblende
3\emph{d} binary ferromagnets, as well as (iii) ferromagnetic and ferrimagnetic
semi- and full-Heusler compounds.Comment: 11 pages, 3 figures, 4 tables; accepted for publication in Phys Rev
Interface properties of the NiMnSb/InP and NiMnSb/GaAs contacts
We study the electronic and magnetic properties of the interfaces between the
half-metallic Heusler alloy NiMnSb and the binary semiconductors InP and GaAs
using two different state-of-the-art full-potential \textit{ab-initio}
electronic structure methods. Although in the case of most NiMnSb/InP(001)
contacts the half-metallicity is lost, it is possible to keep a high degree of
spin-polarization when the interface is made up by Ni and P layers. In the case
of the GaAs semiconductor the larger hybridization between the Ni- and
As- orbitals with respect to the hybridization between the Ni- and P-
orbitals destroys this polarization. The (111) interfaces present strong
interface states but also in this case there are few interfaces presenting a
high spin-polarization at the Fermi level which can reach values up to 74%.Comment: 9 pages, 9 figure
Quasi two-dimensional carriers in dilute-magnetic-semiconductor quantum wells under in-plane magnetic field
Due to the competition between spatial and magnetic confinement, the density
of states of a quasi two-dimensional system deviates from the ideal step-like
form both quantitatively and qualitatively. We study how this affects the
spin-subband populations and the spin-polarization as functions of the
temperature, , and the in-plane magnetic field, , for narrow to wide
dilute-magnetic-semiconductor quantum wells. We focus on the quantum well
width, the magnitude of the spin-spin exchange interaction, and the sheet
carrier concentration dependence. We look for ranges where the system is
completely spin-polarized. Increasing , the carrier spin-splitting,
, decreases, while increasing , increases.
Moreover, due to the density of states modification, all energetically higher
subbands become gradually depopulated.Comment: 3 pages, 3 figure
Towards New Half-Metallic Systems: Zinc-Blende Compounds of Transition Elements with N, P, As, Sb, S, Se, and Te
We report systematic first-principles calculations for ordered zinc-blende
compounds of the transition metal elements V, Cr, Mn with the sp elements N, P,
As, Sb, S, Se, Te, motivated by recent fabrication of zinc-blende CrAs, CrSb,
and MnAs. They show ferromagnetic half-metallic behavior for a wide range of
lattice constants. We discuss the origin and trends of half-metallicity,
present the calculated equilibrium lattice constants, and examine the
half-metallic behavior of their transition element terminated (001) surfaces.Comment: 2nd Version: lattice constants calculations added, text revise
DICHROISME MAGNETIQUE CIRCULAIRE ET ANISOTROPIE MAGNETIQUE DES ALLIAGES A BASE DE METAUX DE TRANSITION
STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF