We have calculated Heisenberg exchange parameters for bcc Fe, fcc Co, and Ni using the nonrelativistic spin-polarized Green-function technique within tight-binding linear muffin-tin orbital method by employing magnetic force theorem to calculate total energy changes associated with a local rotation of magnetization directions. also determined spin-wave stiffness constants found dispersion curves metals in question Fourier transform parameters. Detailed analysis convergence properties...

Effective pair exchange interactions between Mn atoms in III-V and group-IV diluted magnetic semiconductors are determined from a two-step first-principles procedure. In the first step, self-consistent electronic structure of system is calculated for collinear spin at zero temperature with substitutional disorder treated within framework coherent-potential approximation. The effective then obtained second step by mapping total energies associated rotations moments onto an classical...

We demonstrate that the magnetic properties of diluted semiconductors are dominated by short ranged interatomic exchange interactions have a strong directional dependence. By combining first principles calculations with classical Heisenberg model and Monte Carlo simulations, we reproduce observed critical temperatures broad range semiconductors. also show agreement between theory experiment is obtained only when atoms randomly positioned. This suggests ordering heavily influenced...

We present a new method for the determination of electronic structure random transition-metal alloys, which combines simplicity empirical tight-binding schemes with accuracy first-principles treatments. Our uses linear muffin-tin orbitals description states and coherent-potential approximation to describe effect disorder. The central result our theory is expression configurationally averaged Green's-function matrix, then used evaluate various one-electron properties alloys. separation...

The around-the-mean-field version of the LDA+U method is applied to investigate electron correlation effects in δ-Pu. It yields a non-magnetic ground state δ-Pu, and provides good agreement with experimental equilibrium volume, bulk modulus explains important features photoelectron spectra.

Based on model and ab initio calculations we discuss the effect of resonant interface states conductance epitaxial tunnel junctions. In particular show that ``hot spots'' found by several groups in symmetrical barriers ${\mathbf{k}}_{\ensuremath{\Vert}}$-resolved can be explained formation bonding antibonding hybrids between both sides barrier. If resonance condition for these hybrid is met, electron tunnels through barrier without attenuation. Even when move together form a single...

Abstract This contribution reviews an ab initio two-step procedure to determine exchange interactions, spin-wave spectra, and thermodynamic properties of itinerant magnets. In the first step, self-consistent electronic structure a system is calculated for collinear spin at zero temperature. second parameters effective classical Heisenberg Hamiltonian are determined using magnetic force theorem one-electron Green functions. The methods statistical physics employed in subsequent evaluation...

We perform a theoretical study of the magnetism induced in transition metal dioxides ZrO2 and TiO2 by substitution cation vacancy or an impurity from groups 1A 2A periodic table, where is either K Ca. In present both supercell embedded cluster methods are used. It demonstrated that K-impurity leads to robust magnetic moment on surrounding O-atoms for cubic rutile host crystals. On other hand it shown Ca-impurity non state. The native O-vacancy does not induce dioxide crystal.

We study the effect of interface disorder on spin-dependent resistances Co/Cu, Fe/Cr, and Au/Ag multilayers using a newly developed method for calculating transmission matrices from first-principles. The efficient implementation tight-binding linear-muffin-tin orbitals allows us to model large lateral supercells whereby specular diffuse scattering are treated an equal footing. Without introducing any free parameters, quantitative agreement with experiment is obtained. predict that reduces...

The effective exchange interactions of magnetic overlayers Fe/Cu(001) and Co/Cu(001) covered by a Cu-cap layer varying thickness were calculated in real space from first principles. two-dimensional Heisenberg Hamiltonian was constructed used to estimate magnon dispersion laws, spin-wave stiffness constants, overlayer Curie temperatures within the mean-field random-phase approximations. Overlayer temperature oscillates as function cap-layer qualitative agreement with recent experiment.

The canonical method of Andersen and Jepsen for determining the band structure metals, which is based on linear muffin-tin orbital leads to an extremely simple tight-binding method, generalized case random alloys. factorization structural- potential-dependent parts allows one perform configurational averaging within single-site approximation. theory illustrated ${\mathrm{Ag}}_{\mathrm{x}}$${\mathrm{Pd}}_{100\mathrm{\ensuremath{-}}\mathrm{x}}$ alloy series.

We present an ab initio theory of transport quantities metallic ferromagnets developed in the framework fully relativistic tight-binding linear muffin-tin orbital method. The approach is based on Kubo-St\ifmmode \check{r}\else \v{r}\fi{}eda formula for conductivity tensor, coherent potential approximation random alloys, and concept interatomic electron transport. formalism applied to pure $3d$ transition metals (Fe, Co, Ni) Ni-based ferromagnetic alloys (Ni-Fe, Ni-Co, Ni-Mn). High values...

The electronic, magnetic, thermodynamical, and transport properties of FeRh alloys are studied from first principles. We present a unified approach to the phase stability, an estimate exchange interactions in various magnetic phases, including effect temperature which all based on same electronic-structure model. Emphasis is put transition between ferromagnetic (FM) antiferromagnetic (AFM) phases. Such study motivated by recent suggestion as room-temperature memory resistor. theory predicts...

The current-perpendicular-to-plane (CPP) magnetotransport of a metallic sample sandwiched by two ideal leads is described at an ab initio level. so-called ``active'' part the system either trilayer consisting magnetic slabs finite thickness separated nonmagnetic spacer or multilayer formed alternating and layers. We use transmission matrix formulation conductance based on surface Green's functions as formulated means tight-binding linear muffin-tin orbital method. formalism extended to case...

A unified approach to interatomic electron transport within Kubo linear-response theory is sketched that applicable both in semiempirical (matrix-element-based) and ab initio (wave-function-based) tight-binding (TB) techniques. This based on a systematic neglect of the motion inside atomic (Wigner-Seitz) cells leading thus velocity operators describing pure intersite hopping. achieved by using piecewise constant coordinates, i.e., coordinates are cells. The formalism presented simple TB...

The electronic structure and band magnetism of disordered ${\mathrm{Fe}}_{100\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Co}}_{\mathit{x}}$ ${\mathrm{Ni}}_{100\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Cu}}_{\mathit{x}}$ bulk alloys corresponding overlayers on an fcc Cu(001) substrate were studied by means the first-principles tight-binding linear muffin-tin orbital coherent potential approximation method. For Fe-Co system, we found that composition dependence averaged local Fe magnetic...

The effect of structural interface imperfections on the interlayer magnetic coupling is studied theoretically by considering (i) a macroscopic model roughness for possible fluctuations spacer thickness, and (ii) microscopic interdiffusion at ideal interfaces. For Co/Cu/Co(001) system, we found dramatic decrease amplitudes oscillations even small amount imperfections, particularly strong short period oscillations, thus indicating source discrepancy between ab initio calculations experiment....

The authors report the development of a simple and very efficient method for determination Green function an ideal semi-infinite crystal within frame tight-binding linear muffin-tin orbital method. As test method, they calculate k/sub ///-resolved layer densities states Cu(001) Cu(111) surfaces.

A parameter-free electronic structure approach is applied to the study of stability and chemical order in substitutional bcc-based Mo-Ta, Ta-W, Mo-W alloys. The method based on a Green's function description random Configurational treated within generalized perturbation method, temperature effects are accounted for by mean-field approach. practical application this phase Mo-Ta-W alloys tested converting ab initio output thermodynamics three binary subsystems format amenable CALPHAD...

We estimate the anomalous Hall effect of selected Heusler alloys from first principles. An emphasis is put on native disorder which often present in stoichiometric samples. Such can strongly influence both magnetic and transport properties these alloys. employ a recently developed fully relativistic Kubo-St\ifmmode \check{r}\else \v{r}\fi{}eda approach adapted to disordered multisublattice systems chemical described terms coherent potential approximation. As case studies we choose...

The paramagnetic spin-disorder resistivity (SDR) of transition-metal ferromagnets Fe, Co, Ni, ordered transition metal alloys Ni${}_{3}$Mn and Fe${}_{3}$Si as well Ni${}_{2}$Mn$X$ ($X=\text{In}$,Sn,Sb) Heusler is determined from first principles. SDR evaluated similar to the residual by using disordered local moment (DLM) model combined with Kubo-Greenwood linear response calculation. electronic structure within tight-binding muffin-tin orbital method coherent potential approximation (CPA)...

The effect of the Coulomb correlations in diluted magnetic III-V semiconductors has been evaluated using $\mathrm{LSDA}+\mathrm{U}$ (LSDA, local spin-density approximation) correlated band theory method. We show that U plays an important role determination d-Mn states' interaction with semiconductor host valence band. For ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As},$ we found a reasonable value binding energy, agreement experiment....

We present calculations of the exchange interactions and critical temperatures for several diluted magnetic semiconductor systems. It is shown that are dominated by short-ranged have a strong directional dependence. Using combination first-principles together with Monte Carlo simulations classical Heisenberg model, in which positional disorder spin fluctuations properly included, calculated good agreement experimantal observations. between theory experiment, as regards ordering temperatures,...

The around-mean-field $\mathrm{LSDA}+\mathrm{U}$ correlated band theory is applied to investigate the electronic and magnetic structure of $\mathrm{fcc}\text{\ensuremath{-}}\mathrm{Pu}\text{\ensuremath{-}}\mathrm{Am}$ alloys. Despite a lattice expansion caused by Am atoms, neither tendency $5f$ localization nor formation local moments on Pu atoms in $\mathrm{Pu}\text{\ensuremath{-}}\mathrm{Am}$ alloys found. manifolds are calculated, being very similar simple weighted superposition elemental states.