Topic
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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TL;DR: In this paper, an analysis of the itinerant model for antiferromagnetism, in which is included both on-site and inter-site electron correlations, is presented. But it does not consider the band degeneration, which brings into the Hamiltonian the onsite exchange interactions.
Abstract: This is an analysis of the itinerant model for antiferromagnetism, in which is included both on-site and inter-site electron correlations. We also consider the band degeneration, which brings into the Hamiltonian the on-site exchange interactions. The Green function technique is used and the coherent potential approximation (CPA) decoupling for the on-site Coulomb repulsion. This decoupling combined with the modified Hartree–Fock approximation for the inter-site interactions generates the change in shape of the spin bands with growing interaction constants, which is described by the correlation factors and which decreases the kinetic energy of the system. The effective Hartree field and the gain in kinetic energy due to the on-site and inter-site correlation factors drive the antiferromagnetism. The on-site and inter-site interactions act together towards the antiferromagnetism. Their cooperation decreases the interaction constants required for the antiferromagnetic ordering. This new approach allows for the antiferromagnetic instability in the purely itinerant model at the half-filling in the split band limit. This situation describes the high temperature superconducting cuprates.
3 citations
TL;DR: In this article, the half-metallic ferromagnetic properties of the MgH2 hydride with transition metals (TM) were investigated and the Ferromagnetic state energy was computed and compared with the disordered local moment state energy.
Abstract: We show that, in addition to its thermodynamic properties that make it a good candidate for hydrogen storage, the MgH2 hydride exhibits interesting magnetic properties when doped with some transition metals (TM). Using the Korringa–Kohn–Rostoker method (KKR) combined with the coherent potential approximation in the framework of first-principle calculations, we study the half-metallic ferromagnetic properties of the MgH2 doped with TM: Co, V, Cr, Ti; Mg0.95TM0.05H2. The ferromagnetic state energy is computed and compared with the disordered local moment state energy. We show, from the electronic structure, that doping MgH2 with TM elements can convert the material to a half-metallic with a high wide impurity band and high magnetic moment. We have found that the corresponding Curie temperature is bigger than the room temperature, which is considered as a relevant parameter for spintronic applications. Moreover, the mechanism of the hybridization and the interaction between the magnetic ions are also investigated showing that the double exchange is the underlying mechanism responsible for the magnetism of such materials
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3 citations
TL;DR: In this article, the authors employ first principles calculations to study compositional trends in structural and mechanical properties of alloyed titanium aluminides, and show that Mo increases the density of all studied phases, leads to their chemical destabilization with the exception of the ordered bcc β o phase, increases their ductility, and enhances the elastic anisotropy.
3 citations
TL;DR: In this paper, the electronic and magnetic structures of Pd 1− y Ni y alloys were calculated using the charge and spin self-consistent Korringa-Kohn-Rostoker method combined with the coherent potential approximation (KKR-CPA).
3 citations
TL;DR: In this article, the thermal properties of the XY model for spin-1/2 on a linear chain, in the presence of random fields HiSiz, are evaluated using the fermion representation of the Hamiltonian and the coherent potential approximation (CPA).
Abstract: The thermal properties of the XY model for spin-1/2 on a linear chain, in the presence of random fields hiSiz, are evaluated using the fermion representation of the Hamiltonian and the coherent potential approximation (CPA). The specific heat and the thermal conductivity are obtained from the appropriate Green functions. The results are discussed for a model of praseodymium ethyl sulphate (PrES) where the hyperfine interaction is considered to give rise to random fields. This interaction is found to give only a small reduction in the spin specific heat, but to be very effective reducing the spin thermal conductivity. Other mechanisms must be invoked to give a full account of the experimental results.
3 citations