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.

Spin Dependence of the Critical Concentration for the Neel State of 2D Impure Heisenberg Antiferromagnets.

Abstract: The spin-wave theory and the coherent potential approximation are applied to a spin S Heisenberg antiferromagnet with nonmagnetic impurities on square lattice. The impurity effects are taken into account by substituting S (1- x ) for S and using the coherent potential approximation to the exchange interaction, where x is the impurity concentration. At T =0 for S =1/2 the critical impurity concentration x c of the Neel state is 0.303 and the percolation threshold x p is 0.500. The ground state in x c < x < x p is the disordered state with the spin gap. For S ≥1 the long range Neel order vanishes at x p =0.500. These results explain qualitatively the experimental results of La 2 Cu 1- x Mg x O 4 ( S =1/2) and K 2 Mn 1- x Mg x F 4 ( S =5/2). The difference of x c between these materials is caused by the decrease in the magnitude of the effective spin with impurity doping. The spin gap is expected to be observed for La 2 Cu 1- x Mg x O 4 in x c < x < x p at low temperatures.

Computational Nano-Materials Design of Low Cost and High Efficiency Cu$_{2}$ZnSn[Se$_{1-x}$S$_{x}$]$_{4}$ Photovoltaic Solar Cells by Self-Organized Two-Dimensional Spinodal Nanodecomposition

Abstract: We propose the possibility of spinodal nanodecomposition in Cu2ZnSn[Se1-xSx]4 (CZTSeS) for high efficiency photovoltaic solar cells, based on the first-principles calculations within the self-interaction-corrected local density approximation. By using the Korringa–Kohn–Rostoker coherent potential approximation method, electronic structures of CZTSeS are calculated. Due to the calculated positive mixing energy and type II band alignment between Cu2ZnSnSe4 and Cu2ZnSnS4, we can expect that the efficiency of CZTSeS becomes higher by spinodal nano-decomposition. Then we simulate the self-organized two-dimensional spinodal nanodecomposition by Monte Carlo method using the Ising model with chemical pair interactions calculated from the first principles.

Investigation of electronic structure and magnetic properties of CaCo1.86As2 within the CPA method.

Abstract: Recently in iron free arsenide compound CaCo2As2 a 7(1)% of vacancies on the Co sites was detected (Quirinale D G et al 2013 Phys. Rev. B 88 174420). Here we report the investigation of electronic structure and magnetic properties of CaCo1.86As2 within the coherent potential approximation (CPA). First, the CPA calculations are performed on the base of the local spin density approximation. Second, the possible role of Coulomb correlations is checked within the CPA scheme developed recently for strongly correlated systems. Then the spin–orbit coupling, which could be essential for Co, is also taken into account within the CPA calculation. The A type antiferromagnetic ground state and the value of magnetic moment obtained within the CPA approximation are in good agreement with experiment.

Ab-initio Calculation of Half-Metal Ferrimagnetic Sn 0.9 Mn 0.05 Co 0.05 O 2

Abstract: Based on first-principles spin-density functional calculations, using the Korringa–Kohn–Rostoker (KKR) method combined with the coherent potential approximation (CPA), we investigated the half-metallic ferrimagnetic properties of SnO2 codoped with Mn and Co impurities (Sn0.90(Mn0.05, Co0.05)O2) within the self-interaction-corrected (SIC) local density approximation. Mechanism of hybridization and interaction between magnetic ions in Sn0.90(Mn0.05, Co0.05)O2 is investigated. The band structure model has been used to explain the strong ferrimagnetic interaction observed and the mechanism that stabilizes this state is proposed.

Paramagnetic properties of Fe-Mn and Fe-V alloys: a DMFT study.

Abstract: We calculate magnetic susceptibility of paramagnetic bcc Fe-Mn and Fe-V alloys by two different approaches. The first approach employs the coherent potential approximation (CPA) combined with the dynamical mean-field theory (DMFT). The material-specific Hamiltonians in the Wannier function basis are obtained by density functional theory. In the second approach, we construct supercells modeling the binary alloys and study them using DMFT. Both approaches lead to a qualitative agreement with experimental data. In particular, the decrease of Curie temperature with Mn content and a maximum at about 10 at.% V are well described in units of the Curie temperature of pure iron. In contrast to the Mn impurities, the V ones are found to be antiferromagnetically coupled to Fe atoms. Our calculations for the two-band Anderson-Hubbard model indicate that the antiferromagnetic coupling is responsible for a maximum in the concentration dependence of Curie temperature in Fe-V alloys.