Based upon the observations (i) that their in-plane lattice constants match almost perfectly and (ii) electronic structures overlap in reciprocal space for one spin direction only, we predict perfect filtering interfaces between graphite (111) fcc or (0001) hcp Ni Co. The is quite insensitive to roughness disorder. formation of a chemical bond open d-shell transition metals might complicate even prevent injection into single graphene sheet can be simply prevented by dusting Co with few...

We demonstrate how ab initio cluster calculations including the full Coulomb vertex can be done in basis of localized, generalized Wannier orbitals which describe low-energy density functional (LDA) band structure infinite crystal, e.g. transition metal 3d and oxygen 2p orbitals. The spatial extend our (orthonormalized Nth order muffin-tin orbitals) is close to that found for atomic Hartree-Fock define Ligand as those linear combinations O couple chosen cluster. use ligand allows a minimal...

The interface-induced magnetization damping of thin ferromagnetic films in contact with normal-metal layers is calculated from first principles for clean and disordered Fe/Au Co/Cu interfaces. Interference effects arising coherent scattering turn out to be very small, consistent a small magnetic coherence length. Because the mixing conductances which govern spin transfer are good approximation real valued, pumping can described by an increased Gilbert factor but unmodified gyromagnetic...

The in-plane lattice constants of close-packed planes fcc and hcp Ni Co match that graphite almost perfectly so they share a common two-dimensional reciprocal space. Their electronic structures are such overlap in this space for one spin direction only allowing us to predict perfect filtering interfaces between (111) or (0001) Co. First-principles calculations the scattering matrix show is quite insensitive amounts interface roughness disorder which drastically influence spin-filtering...

Landauer's formula relates the conductance of a quantum wire or interface to transmission probabilities. Total probabilities are frequently calculated using Green function techniques and an expression first derived by Caroli. Alternatively, partial can be from scattering wave functions that obtained matching in region Bloch modes ideal bulk leads. An elegant technique for doing this, formulated originally Ando, is here generalized any Hamiltonian represented tight-binding form. A more...

Details are presented of an efficient formalism for calculating transmission and reflection matrices from first principles in layered materials. Within the framework spin density functional theory using tight-binding muffin-tin orbitals, scattering determined by matching wave functions at boundaries between leads which support well-defined states, region. The calculation scales linearly with number principal layers $N$ region as cube atoms $H$ lateral supercell. For metallic systems required...

The spin dependence of the interface resistance between ferromagnetic Fe and InAs is calculated from first principles for specular disordered (001) interfaces. Because symmetry mismatch in minority-spin channel, acts as an efficient filter with a transmitted current polarization 98% 89%. diffusive regime comparable to few microns bulk InAs. Symmetry breaking arising disorder reduces asymmetry substantially, we conclude that injection into can only be realized using high-quality epitaxial

A systematic, quantitative study of the effect interface roughness and disorder on magnetoresistance FeCo$|$vacuum$|$FeCo magnetic tunnel junctions is presented based upon parameter-free electronic structure calculations. Surface found to have a very strong spin-polarized transport while that in leads (leads consisting substitutional alloy) weaker but still sufficient suppress huge tunneling magneto-resistance (TMR) predicted for ideal systems.

Abstract The conductance of nanoscale structures can be conveniently related to their scattering properties expressed in terms transmission and reflection coefficients. Wave function matching (WFM) is a transparent technique for calculating matrices any Hamiltonian that represented tight‐binding form. A first‐principles Kohn–Sham on localized orbital basis or real space grid has such WFM based upon direct the scattering‐region wave Bloch modes ideal leads used probe region. purpose this...

We present the formalism and demonstrate use of overlapping muffin-tin approximation.This fits a full potential to superposition spherically symmetric short-ranged wells plus constant.For one-electron potentials this form, standard multiple-scattering methods can solve Schrödingers' equation correctly 1st order in overlap.Choosing an augmented-plane-wave method as source potential, we illustrate procedure for diamond-structured Si.First, compare Si-centered approximation with then...

As devices are reduced in size, interfaces start to dominate electrical transport, making it essential be able describe reliably how they transmit and reflect electrons. For a number of nearly perfectly lattice-matched materials, we calculate from first principles the dependence interface transparency on crystal orientation. Quite remarkably, largest anisotropy is predicted for between prototype free-electron materials silver aluminum, which massive factor 2 difference (111) (001) found.

Ultrafast demagnetization induced by femtosecond laser pulses in thin metallic layers is caused the outflow of spin-polarized hot electron currents describable superdiffusive transport model. These laser-generated spin can cross interface into another magnetic layer and give rise to magnetization dynamics valves with noncollinear magnetizations. To describe ultrafast such nanostructures we develop here theory for general multilayers. Specifically, introduce an Al/Ni/Ru/Fe/Ru multilayer...

The spin dynamics of photoexcited carriers in semiconductors contact with a ferromagnet is treated theoretically and compared time-dependent Faraday rotation experiments. long-time response the system found to be governed by first tens picoseconds which excited plasma interacts strongly intrinsic interface between semiconductor spite existence Schottky barrier equilibrium.

The exceptionally high mobility of carriers in graphene is one its defining characteristics, especially view potential applications.Therefore it both practical and fundamental importance to understand the mechanisms responsible for limiting values mobility.The aim paper study theoretically such mechanism, i.e. scattering on ripples.The transport properties rippled are studied using single-band tight-binding model.Both bond-length variation, corresponding vector effective mass picture,...

The theory of charge and spin transport in forward-biased Schottky barriers reveals characteristic experimentally relevant features. conductance mismatch is found to enhance the current induced spin-imbalance semiconductor. GaAs|MnAs interface resistance obtained from an analysis magnetic field dependent Kerr rotation experiments by Stephens et al. compared with first-principles calculations for intrinsic interfaces. With increasing bias, transparency grows towards theoretical values,...

In terms of the state-of-the-art first principle computational methods combined with numerical renormalization group technique spectroscopic properties Co adatoms deposited on silicene are analyzed. By establishing an effective low-energy Hamiltonian based calculations, we study behavior local density states adatom external parameters, such as magnetic field and gating. It is shown that Kondo resonance temperature order a few Kelvins can emerge by fine-tuning chemical potential. The...

It is common to describe graphene as ideally at plane, however there exists both theoretical and experimental evidence that it most usual nd in a rippled state.The ripples can be either induced by the substrate or formed spontaneously suspended graphene.The lateral size of such features ranges between several tens nanometers with height up 1 nm.It has been suggested presence could one factors ultimately limiting mobility carriers may also responsible, introducing an eective gauge eld, for...

A theoretical description of spin current injection from a nonmagnetic layer into magnetic one is presented, with the main emphasis on and determination penetration depth component transverse to magnetization. This also determines transfer torque generation. Physically, may be driven by an external electric field or temperature gradient. To determine we used ab initio calculations channel mixing conductances as well transmission. The results are then second harmonic voltage response, which...

We present a theoretical description of spin-transfer torque in spin valve with perpendicularly magnetized polarizer. The polarizer consisting several ultrathin layers is considered as single interfacial magnetic scatterer between two nonmagnetic layers, and included the theory based on diffusive transport via appropriate boundary conditions. model has been used to study systematically current-induced switching both perpendicular in-plane polarizers free layer. wave-function matching ab...

Thanks to its outstanding electronic properties, like very high mobility of carriers, graphene has emerged in recent years as exciting candidate for use new devices.When it is patterned the form ribbons with widths range nanometers, transport properties become strongly influenced by presence states localized at edges ribbon.Using first principles calculations we study these both isolated and metallic electrodes.The were performed end contacted geometry i.e. sheets right angle electrodes.Both...

It is shown that the current-perpendicular-to-plane giant-magnetoresistance (CPP-GMR) oscillations, in ballistic regime, are strongly correlated with those of exchange coupling (J). Both GMR and J treated on an equal footing within a rigorously solvable tight-binding single-band model. The strong correlation consists asymptotic sharing same period, determined by Fermi surface, oscillations varying spacer thickness predominantly opposite phases.

The spin-dependence of the interface resistance between ferromagnetic Fe and InAs is calculated from first-principles for specular disordered (001) interfaces. Because symmetry mismatch in minority-spin channel, acts as an efficient spin filter with a transmitted current polarisation 98 89%. diffusive regime comparable to few microns bulk InAs. Symmetry-breaking arising disorder reduces asymmetry substantially we conclude that injection into can only be realized using high quality epitaxial

We present the formalism and demonstrate use of overlapping muffin-tin approximation (OMTA). This fits a full potential to superposition spherically symmetric short-ranged wells plus constant. For one-electron potentials this form, standard multiple-scattering methods can solve Schr\"{o}dingers' equation correctly 1st order in overlap. Choosing an augmented-plane-wave method as source potential, we illustrate procedure for diamond-structured Si. First, compare Si-centered OMTA with then...

Based on reliable ab initio computations and the numerical renormalization group method, systematic studies a two-dimensional GaSe monolayer with Co adatoms have been carried out. It is shown that stable lowest-energy configuration of system involves adatom located over Ga atom. For such configuration, it demonstrated electronic magnetic properties can be effectively controlled by means external factors, as field, gate voltage, or temperature. Moreover, if properly tuned, GaSe-Co also...