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.

Anomalous thermal transport in disordered harmonic chains and carbon nanotubes

Abstract: We report the coherent potential approximation method of treating quantum thermal transport properties of nanoscale systems with mass disorder. Instead of massive efforts required in brute-force calculations, configuration averaging of disordered systems can be efficiently handled in a self-consistent manner by setting up the phonon version of nonequilibrium vertex correction theory. The accuracy of the method is verified by comparing with the exact results and Monte Carlo experiments in one-dimensional atomic chains. Results obtained for disordered harmonic chains and carbon nanotubes provide evidence of anomalous thermal transport in such systems. We also observe crossover in the transport where phonon scattering by disorder becomes important. Our results show that disorder plays a role in thermal conductance reduction.

Materials design of interstitial Be-doped ferromagnetic (In,Fe)As

Abstract: Using the first-principles calculation method, we study the ferromagnetic states of electron-doped (In,Fe)As by the Korringa–Kohn–Rostoker coherent potential approximation method and calculate Curie temperature (TC) by Monte Carlo simulation. We show that the chemical pair interactions and magnetic exchange interactions between Fe atoms depend on the concentration of the doped interstitial Be donor. We obtain the so-called ordered phase of Fe-rich regions in this material. With this type of structure, Be-doped (In,Fe)As can exhibit ferromagnetism and its TC could be up to approximately 85 K. We propose that the ordered phase is necessary for enhancing ferromagnetism and increasing TC.

Self-consistent theory of heavy-fermion alloys

Abstract: In the present article, a theory describing the normal state of heavy-fermion alloys is presented which is based on the Yoshimori-Kasai model in the framework of a slave-boson mean-field theory under the coherent-potential approximation. The density of states (DOS) and its concentration dependence for conduction electrons and strongly correlated f electrons in heavy-fermion alloys are calculated self-consistently. The results obtained not only reveal the process of the pseudogap formation in the DOS, but also give a reasonable explanation of the low-temperature coherence effects in the specific heat, the thermoelectric power, and the molar residual resistivity for heavy-fermion alloys.

Many-body CPA for the Holstein double-exchange model

Abstract: A many-body coherent potential approximation (CPA) previously developed for the double exchange (DE) model is extended to include coupling to local quantum phonons. The Holstein-DE model studied (equal to the Holstein model for zero Hund coupling) is considered to be a simple model for the colossal magnetoresistance manganites. We concentrate on effects due to the quantisation of the phonons, such as the formation of polaron subbands. The electronic spectrum and resistivity are investigated for a range of temperature and electron-phonon coupling strengths. Good agreement with experiment is found for the Curie temperature and resistivity with intermediate electron-phonon coupling strength, but phonon quantisation is found not to have a significant effect in this coupling regime.