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.

On the magnetization fluctuations in the completely disordered paramagnetic medium

Abstract: The space extension of a single magnetization fluctuation in the disordered paramagnetic medium defined within the coherent potential approximation is discussed. The thermodynamical potential functional for the subspace of nearly completely disordered configurations is derived.

Concentration dependence of the local oscillation spectrum in V-Be α solutions

Abstract: Cold neutron inelastic scattering is used to investigate the dynamics of alpha solutions of Be in a V matrix for various concentrations. The increase of Be concentration leads to a broadening of the local oscillation (LO) spectrum and to a shift of its centre. The concentration dependence of the LO spectrum width and LO energy position, as well as the deformation of the lattice vibrations spectrum are compared with calculations in terms of the coherent potential approximation.

Quantum many-body theory and coherent potential approximation

Abstract: The coherent potential approximation (CPA) is a useful method for describing the electron correlations as well as the effects of disorder on electrons. Among the many-body theories using the CPA, the dynamical CPA, the many-body CPA, and the dynamical mean-field theory are reviewed to clarify how these theories use the CPA concept for the description of the electron correlations. The theories characterized by the momentum independent self-energy are shown to interpolate between the weak and strong Coulomb interaction limits, and therefore describe the basic properties of magnetism from metals to insulators, the metalinsulator transition, and the single particle excitations from the Fermi liquid to the insulator. The relation among various theories are clarified. In particular, it is shown that the dynamical CPA, the many-body CPA, and the dynamical mean-field theory are equivalent to each other, so that the theories of itinerant magnetism and those of the strongly correlated electron systems are unified within the single-site approximation. The nonlocal effects on the selfenergy are also discussed beyond the single-site approximation.

Magnetism of 3d transition metal atoms on W(001): submonolayer films

Abstract: We have investigated random submonolayer films of 3d transition metals on W(001). The tight-binding linear muffin-tin orbital method combined with the coherent potential approximation was employed to calculate the electronic structure of the films. We have estimated local magnetic moments and the stability of different magnetic structures, namely the ferromagnetic order, the disordered local moments and the non-magnetic state, by comparing the total energies of the corresponding systems. It has been found that the magnetic moments of V and Cr decrease and eventually disappear with decreasing coverage. On the other hand, Fe retains approximately the same magnetic moment throughout the whole concentration range from a single impurity to the monolayer coverage. Mn is an intermediate case between Cr and Fe since it is non-magnetic at very low coverages and (ferro)magnetic otherwise.

Co-, Fe-, Ni-doped and co-doped rutile GeO₂: insights from ab-initio calculations

Abstract: Abstract Rutile germanium oxide (rutile GeO 2 ), a semiconductor, can act as a half-metallic compound and is a promising material for spintronic and optoelectronic applications. Calculations were performed using the Korringa–Kohn–Rostoker (KKR) approach and the coherent potential approximation (CPA), which were further combined with two approximations, the local density approximation (LDA) and the self-interaction corrected LDA approximation (LDA-SIC), to study the electronic structure of bulk rutile GeO 2 doped and co-doped with three transition-metal impurities: Fe, Co, and Ni. The doping value was set to 10%, while the co-doping level was set to 5% for each impurity. The main findings of this work are: (1) a direct ultrawide bandgap of 4.80 eV is observed and the rutile GeO 2 exhibits an N-type semiconducting property. (2) Doped and co-doped GeO 2 acquire a magnetic behavior and exhibit half-metallicity. (3) The mechanism responsible for these properties is also studied. (4) The critical temperature can reach 334 K when GeO 2 is doped with Fe, while it rises to 398 K when it is co-doped with Fe and Co. (5) The spin polarization can be improved by co-doping. It can be inferred that rutile GeO 2 doped or co-doped with (Co, Fe) transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.