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Correlated Electron Systems (correlated + electron_system)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Dynamical CPA theory of magnetism , harmonic approximation

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003
Y. Kakehashi
Abstract We have developed the dynamical coherent potential approximation (CPA) to the correlated electron system on the basis of the functional integral method and the harmonic approximation. The theory becomes exact in the high temperature limit, reproduces the results of the second order perturbation theory for small Coulomb interaction, and takes into account the terms to describe the strong correlation limit. The numerical calculations show that the theory describes the Curie,Weiss susceptibility, a large reduction of the Curie temperature due to the dynamical effects, and a many-body satellite peak as well as a band narrowing in the density of states. [source]

Energy transfer to phonons after photoexcitation in one-dimensional correlated electron-phonon systems

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009
Kenji Yonemitsu
Abstract In order to study relaxation rates of photoexcited states in correlated electron systems, we calculate the time evolution of phonons' kinetic energies after photoexcitation of a one-dimensional half-filled Hubbard model coupled with different types of phonons, which modulate transfer integrals, site energies, and on-site repulsion strengths. Without or with weak dimerization, the energy transfer to phonons that modulate on-site repulsion strengths is the largest. It increases rapidly as a function of the corresponding displacement. This suggests that the rapid relaxation of photoexcited states in one-dimensional correlated electron systems is allowed without change in symmetry by phonons that modulate Coulomb repulsion strengths. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Quasi-particle peak due to magnetic order in strongly correlated electron systems

ANNALEN DER PHYSIK, Issue 8 2010
T.A. Zaleski
Abstract We study the electron spectral function of the antiferromagnetically ordered phase of the three dimensional Hubbard model, using recently formulated low-energy theory based on the 2D half-filled Hubbard model which describes both collective spin and charge fluctuations for arbitrary value of the Coulomb repulsion U. The model then is solved by a saddle-point approximation within the CP1 representation for the Neel field. The single-particle properties are obtained by writing the fermion field in terms of a U(1) phase, Schwinger boson SU(2) fields and a pseudofermion variables. We demonstrate that the appearance of a sharp peak in the electron spectral function in the antiferromagnetic state points to the emergence of the bosonic mode, which is associated with spin ordering. [source]