Coherent potential approximation

About: Coherent potential approximation is a research topic. Over the lifetime, 1930 publications have been published within this topic receiving 36805 citations.

The electronic structure of Pd-Pt random alloys: a relativistic KKR-CPA calculation

Abstract: By applying a new method for solving the equations of the relativistic Korringa-Kohn-Rostoker-coherent-potential approximation. The authors have been able to study the electronic structure of compositionally disordered Pd-Pt alloys. This investigation was carried out, on the one hand, to test the reliability of the method itself and, on the other, to learn whether a 'rigid band' picture is appropriate for these alloys as suggested by an interpretation of residual resistivity measurements. They find that the method is numerically stable and can now be safely incorporated into a self-consistent-field local-density theory for alloys with heavy elements. Moreover, the electronic structure of Pd-Pt is found to be 'non-rigid-band' like and demonstrates some interesting new features arising from mass-velocity, Darwin and spin-orbit coupling effects.

Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations

Abstract: Using ab initio calculations on Zn0.975− x Fe0.025Cu x O (x = 0, 0.01, 0.02, 0.05), we study the variations of magnetic moments vs Cu concentration. The electronic structure is calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Fe increase on increasing Cu content. From the density of state (DOS) analysis, we show that Cu-induced impurity bands can assure, by two mechanisms, the enhancement of Fe magnetic moment in Zn0.975− x Fe0.025Cu x O.

Electronic Structures of a Quantum Well of A1–xBx Alloy Semiconductor in the Coherent Potential Approximation

Abstract: We have theoretically studied the electronic and optical properties of a quantum well (QW) in which the well region is constructed from a binary alloy semiconductor A 1-x B x in the coherent potential approximation (CPA). A tight binding model is used for a single particle (electron, hole, Frenkel exciton) in the well composed by a rectangular array of N x x N y x N z sites. The effect of the diagonal randomness is reduced to the coherent potential Σ(E), which is assumed to be the same for all sites, and is selfconsistently determined with the average Green's function. For a slab (oo, ∞, N z ) and wire (∞, N y , N z ), the density of states?(E) is composed of N z (or N y x N z ) subbands, each shows the two (one)-dimensional van-Hove singularity. When x (or 1 - x) is small, a B (A) impurity-band always appears at the lower (higher) energy side of the lowest (highest) host-band. As the well width becomes narrower and/or the dimensionality decreases, the boundary for Δ/t decreases which separates the amalgamation type and the persistence type.

Local environment effects in the magnetic properties and electronic structure of disordered FePt

Abstract: Local aspects of magnetism of disordered FePt are investigated by ab initio fully relativistic full-potential calculations, employing the supercell approach and the coherent potential approximation (CPA). The focus is on trends of the spin and orbital magnetic moments with chemical composition and with bond lengths around the Fe and Pt atoms. A small but distinct difference between average magnetic moments obtained when using the supercells and when relying on the CPA is identified and linked to the neglect of the Madelung potential in the CPA.

Magnetism and half-metallicity of some Cr-based alloys and their potential for application in spintronic devices

Abstract: We present results of the exchange interactions and Curie temperatures in some Cr-based chalcogenides and pnictides. The calculations are performed mostly for Zinc Blende (ZB) structure with the lattice parameter varying between 5.45 and 6.6 A, appropriate for some typical II-VI and III-V semiconducting substrates. Electronic structure is calculated via the linear muffintin-orbitals method and disorder effects, when appropriate, are taken into account via the coherent potential approximation. Calculated exchange interactions are used to estimate the Curie temperature by employing the mean-field and the random phase approximations. For CrTe we compare the results of the ZB and Rock-Salt (RS) structures.