197 research outputs found
Interface effects at a half-metal/ferroelectric junction
Magnetoelectric effects are investigated ab-initio at the interface between
half-metallic and ferroelectric prototypes: Heusler CoMnSi and perovskite
BaTiO. For the Co-termination ferroelectricity develops in BaTiO down
to nanometer thicknesses, whereas for the MnSi-termination a paraelectric and a
ferroelectric state energetically compete, calling for a full experimental
control over the junction atomic configuration whenever a ferroelectric barrier
is needed. Switch of the electric polarization largely affects magnetism in
CoMnSi, with magnetoelectric coupling due to electronic hybridization at
the MnSi termination and to structural effects at the Co-termination.
Half-metallicity is lost at the interface, but recovered already in the
subsurface layer.Comment: 4 pages, 3figures, accepted for publication in Appl. Phys. Let
Charge-induced spin polarization in non-magnetic organic molecule Alq
Electrical injection in organic semiconductors is a key prerequisite for the
realization of organic spintronics. Using density-functional theory
calculations we report the effect of electron transfer into the organic
molecule Alq. Our first-principles simulations show that electron injection
spontaneously spin-polarizes non-magnetic Alq with a magnetic moment
linearly increasing with induced charge. An asymmetry of the Al--N bond lengths
leads to an asymmetric distribution of injected charge over the molecule. The
spin-polarization arises from a filling of dominantly the nitrogen
orbitals in the molecule's LUMO together with ferromagnetic coupling of the
spins on the quinoline rings.Comment: Accepted 4 pages 4 figure
Magnetization dynamics in disordered FeCo alloys : A first-principles augmented space approach and atomistic spin dynamics simulations
In this paper, we present a general method to study magnetization dynamics in
chemically disordered alloys. This computationally feasible technique, which
seamlessly combines three approaches : the density functional based linear
muffin-tin orbitals (LMTO) for self-consistently obtaining a sparse
Hamiltonian; the generalized recursion method to obtain the one and
two-particle Green functions and augmented space approach to deal with disorder
averaging. The same formalism applied to both spectral and response properties
should make the errors compatible in different studies. %The underlying
computational routines are optimized and parallelized for ease of handling. We
have demonstrated a successful application to the binary chemically disordered
FeCo alloys to explain several experimental features in magnon
spectra. Our study captures significant magnon softening due to magnon-electron
scattering for chemically disordered FeCo alloys within linear spin
wave regime. As a complementary study, we have done atomistic spin dynamics
simulations by solving Landau-Lifshitz-Gilbert equation with parameters
obtained from ab initio multiple scattering theory to compare with the results
obtained from augmented space approach.Comment: arXiv admin note: text overlap with arXiv:1102.4551, arXiv:1304.7091
by other author
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