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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.


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Proceedings ArticleDOI
01 Jan 1976
TL;DR: The split-band model was used in this paper to explain the spin-down bands of f.c.c alloys and explain many of their properties, such as the anomalous Hall coefficient and magnetic resistivity.
Abstract: In concentrated alloys where the nuclear charges or exchange fields of the components differ sufficiently, the coherent potential approximation predicts that each alloy component has its own 3d band, having minimal overlap with the 3d bands of other components. As we pointed out earlier, this “split‐band model” applies well to the spin‐down bands of f.c.c. Ni‐Fe, Ni‐Fe‐Cu, etc., and explains many of their properties. For example, several physical quantities exhibit anomalies when the Fermi level eF crosses the boundary T between nickel and iron bands. A systematic search for b.c.c. iron‐base alloy series where the spin‐up band might be split, and where eF might cross a boundary T between bands, yields Fe‐V. As expected, the electronic specific heat coefficient γ of Fe‐V has a minimum when eF is at T, around 15 at % V. The electrical resistivity ρ, the slope ρ−1 dρ/dH, and the anomalous Hall coefficient Rs have sharp anomalies close by. The magnetoresistance Δρ/ρo is unusually large in Fe‐V. A scattering r...

8 citations

Journal ArticleDOI
TL;DR: In this article, the strong in-plane anisotropy seen in angle-resolved photoemission of the well-known iron pnictide prototype compounds BaFe2As2 and Ba(Fe1-xCox)(2)As-2 in their low-temperature antiferromagnetic phases is investigated.
Abstract: By means of one-step model calculations the strong in-plane anisotropy seen in angle-resolved photoemission of the well-known iron pnictide prototype compounds BaFe2As2 and Ba(Fe1-xCox)(2)As-2 in their low-temperature antiferromagnetic phases is investigated. The fully relativistic calculations are based on the Korringa-Kohn-Rostoker-Green function approach combined with the coherent potential approximation alloy theory to account for the disorder induced by Co substitution on Fe sites in a reliable way. The results of the calculations can be compared directly to experimental spectra of detwinned single crystals. One finds very good agreement with experiment and can reveal all features of the electronic structure contributing to the in-plane anisotropy. In particular the local density approximation can capture most of the correlation effects for the investigated system without the need for more advanced techniques. In addition, the evolution of the anisotropy for increasing Co concentration x in Ba(Fe1-xCox)(2)As-2 can be tracked almost continuously. The results are also used to discuss surface effects and it is possible to identify clear signatures to make conclusions about different types of surface termination.

8 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied the disorder-induced smearing of the density of states in a two-dimensional electron system taking into account a spin-orbit term in the Hamiltonian of a free electron.
Abstract: We study theoretically the disorder-induced smearing of the density of states in a two-dimensional electron system taking into account a spin-orbit term in the Hamiltonian of a free electron. We show that the characteristic energy scale for the smearing increases with increasing the spin-orbit coupling. We also demonstrate that in the limit of a strong spin-orbit coupling the diagrams with self-intersections give a parametrically small contribution to the self-energy. As a result, the coherent potential approximation becomes asymptotically exact in this limit. The tail of the density of states has the energy scale which is much smaller than the magnitude of the smearing. We find the shape of the tail using the instanton approach.

8 citations

Journal ArticleDOI
TL;DR: In this article, a generalised Hartree-Fock approximation is made for the interaction and the coherent potential approximation for configurational average over the sites of randomly distributed impurity spins, and a reduction of the density of states due to the Kondo effect is found at the Fermi level.
Abstract: Electronic properties of a highly doped Kondo system are discussed. The method of expressing the s-d exchange interaction in terms of the two kinds of quasi-spins, proposed by one of the authors (Kurata (1970)) for the single-impurity Kondo problem, is extended to this system. A generalised Hartree-Fock approximation is made for the interaction and the coherent potential approximation for configurational average over the sites of randomly distributed impurity spins. The density of states of conduction electrons and electrical resistivity are calculated for various concentrations of impurity spins. A reduction of the density of states due to the Kondo effect is found at the Fermi level.

8 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the electronic structure of the substitutionally disordered transition metal dihydride series Ti1-nbyHx, Ti 1-yVyHx (0.5 ⩽ y⩽ 1; 1.5 µm x µm 2.0) and found that trends in the region of the Fermi level display rigid band-like characteristics for the substitution of niobium or vanadium for titanium, and for the hydrogen disorder as well.
Abstract: Employing the tight binding coherent potential approximation method, we investigated the electronic structure of the substitutionally disordered transition metal dihydride series Ti1-yNbyHx, Ti1-yVyHx (0 ⩽ y ⩽ 1; 1.5 ⩽ x ⩽ 2.0). These alloys contain disorder on both the metal and hydrogen sublattices. We found that trends in the region of the Fermi level display rigid band-like characteristics for the substitution of niobium or vanadium for titanium, and for the hydrogen disorder as well. The calculations are compared with electronic specific heat measurements and predictions based on nuclear magnetic resonance experiments.

8 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
202222
202127
202030
201930
201840