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.

Application of the Korringa-Kohn-Rostoker cluster coherent-potential approximation to an s phase shift semicircular model

Abstract: An s phase shift semicircular model of a random substitutional binary alloy has been used as a test case for studying the self-consistent Korringa-Kohn-Rostoker cluster coherent-potential approximation (KKR-CCPA). In addition to being computationally simpler, the model has the advantage that a corresponding model exists in the well known tight-binding framework. A one-to-one correspondence has been shown between the KKR-CCPA equations and the tight-binding CCPA equations. In the tight-binding framework, it has been shown that certain quantities, which were hitherto calculated approximately, can be obtained exactly by the partitioning technique. Results for density of states in the CCPA show rich structure in the impurity band, which arises due to correlated scattering from clusters of atoms.

Theory for effects of pressure on heavy-fermion alloys

Abstract: The effects of pressure on heavy-fermion alloys are studied in the framework of the Yoshimori-Kasai model under the coherent potential approximation. A unified picture is presented for both electron-type heavy-fermion systems and hole-type heavy-fermion systems. The density of states of f electrons is calculated over the whole range of doping concentration under applied pressure. The Kondo temperature, the specific-heat coefficient, and the electrical resistivity are obtained, in agreement with the experiments qualitatively. The contrasting pressure-dependent effects for two types of heavy-fermion alloys are discussed to reveal the coherence in the system under pressure.

B-doped diamond: Superconductivity without Fermi surface

Abstract: We consider superconductivity in boron (B) doped diamond using a simplified model for the valence band of diamond. We treat the substitutional disorder of B ions by the coherent potential approximation and the attractive force between holes by the ladder approximation under the assumption of instantaneous interaction. We thereby calculate the quasiparticle life time, the evolution of the single-particle spectra due to doping, and the effect of disorder on the critical temperature Tc. We in particular compare our results with those for supercell calculations to see the role of disorder, which turns out to be of crucial importance.

On the Existence of Spin Glass Region in Alloys between Ferro- and Antiferro-Magnetic Metals

Abstract: The magnetic structure in the ground state of alloys between the ferromagnetic and the antiferromagnetic metals is investigated by using the coherent potential approximation (CPA) combined with the Hartree-Fock (HF) approximation for the Hubbard Hamiltonian. By bearing in mind Fe-Cr alloys, the successive transitions from the ferromagnetic state to the antiferromagnetic one via the spin glass one with varying the alloy composition are demonstrated by the HF-CPA calculation, which distinguishes Fe atoms with magnetic moments parallel to the bulk magnetization or the sublattice one from those with antiparallel moments. An overall agreement between various magnetic measurements on Fe-Cr and the present calculation is obtained.

The coherent potential approximation in disordered semiconducting alloys

Abstract: The success of the coherent potential approximation (CPA) in obtaining semiquantitative theoretical descriptions of the electronic structure and the transport, optical, and magnetic properties of disordered metallic alloys has been recognized for some time. A more limited number of applications has been made to group IV and III–V alloys. This article reviews some of the aspects of the CPA relevant to the semiconductor problem. The theory is illustrated by new results for the complex band structure of disordered (Hg1−xCdx)Te, obtained by use of an empirical tight‐binding scheme and the parameters of Czyzyk and Podgorny for HgTe and CdTe.