Journal ArticleDOI
Paramagnetic Ni Cu Alloys: Electronic Density of States in the Coherent-Potential Approximation
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TLDR
In this paper, the effects of alloying on a highly asymmetric model density of states characteristic of some of the features of the densities of states in fcc transition metals are considered in detail.Abstract:
The coherent-potential approximation (CPA) is extended to study general band shapes and systems having orbital degeneracy. This permits its application to realistic systems, in particular the $\mathrm{Ni}\mathrm{Cu}$ alloys. The effects of alloying on a highly asymmetric model density of states characteristic of some of the features of the density of states in fcc transition metals are considered in detail. A model Hamiltonian for paramagnetic $\mathrm{Ni}\mathrm{Cu}$ is constructed using a basis of orthogonalized plane waves and tight-binding $d$ functions. Orbital degeneracy and hybridization are treated as in paramagnetic Ni. Effects of alloying are assumed to be restricted to the diagonal elemensts of the $d\ensuremath{-}d$ block. The model is applicable to the Ni-rich alloys, as is the approximation used to obtain simple solutions of the full CPA equations. The results are consistent with recent photoemission data on $\mathrm{Ni}\mathrm{Cu}$, and with the "minimum polarity" hypothesis used by Lang and Ehrenreich. They are incompatible with the rigid-band model because the scattering potential of the random alloy is strong compared to the peak widths. Rather than a rigid shift of the density of states, the calculated concentration dependence shows that the main peaks remain stationary while changing magnitude and shape. Decomposition of the total density of states into Ni and Cu contributions confirms that, for the expected position of the Fermi level, the $d$ holes are located primarily on Ni sites.read more
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Journal ArticleDOI
The theory and properties of randomly disordered crystals and related physical systems
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Valence fluctuation phenomena
TL;DR: In this article, the authors review the experimental results observed in the subset of rare-earth systems for which the 4f ions form a lattice with identical valence on each site, and discuss key thermodynamic experiments, such as susceptibility and lattice constant, and spectroscopic experiments such as XPS and neutron scattering.
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Itinerant electron magnetism
TL;DR: The many theoretical studies of the various magnetic, thermal and magnetoelastic properties for paramagnetic and ferromagnetic transition metals and alloys in the simple itinerant electron model are reviewed in this article.
Book ChapterDOI
The Electronic Structure of Alloys
H. Ehrenreich,L.M. Schwartz +1 more
TL;DR: In this paper, the authors present a discussion on the electronic properties of binary substitutional alloys within the single particle approximation, and present a didactic exposition of the equilibrium properties.
Journal ArticleDOI
Calculated surface segregation in transition metal alloys
TL;DR: In this article, a combination of numerical techniques was used to calculate the heat of solution, surface energies and segregation energies for a large number of metals and alloys, including Ni and Rh 75 Pt 25.