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Effective mass (solid-state physics)
About: Effective mass (solid-state physics) is a research topic. Over the lifetime, 12539 publications have been published within this topic receiving 295485 citations.
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TL;DR: In this article, the Mott transition was investigated using a cluster extension of dynamical mean field theory (DMFT), and no evidence for a finite temperature Mott critical point was found.
Abstract: We investigate the Mott transition using a cluster extension of dynamical mean field theory (DMFT). In the absence of frustration we find no evidence for a finite temperature Mott transition. Instead, in a frustrated model, we observe signatures of a finite temperature Mott critical point in agreement with experimental studies of $\ensuremath{\kappa}$ organics and with single-site DMFT. As the Mott transition is approached, a clear momentum dependence of the electron lifetime develops on the Fermi surface with the formation of cold regions along the diagonal direction of the Brillouin zone. Furthermore, the variation of the effective mass is no longer equal to the inverse of the quasiparticle residue, as in DMFT, and is reduced approaching the Mott transition.
98 citations
TL;DR: In this article, the electrical and optical properties of n-type germanium have been studied for doping levels greater than 5×1018 cm−3, and the electron mobility depends upon the specific group V donor used as a dopant and, at a given carrier concentration, increases in the order μAs<μP<μSb.
Abstract: The electrical and optical properties of n‐type germanium have been studied for doping levels greater than 5×1018 cm−3. Hall coefficient and resistivity measurements show that the electron mobility μ depends upon the specific group V donor used as a dopant and, at a given carrier concentration, increases in the order μAs<μP<μSb. In material doped very heavily with arsenic, a large fraction of the arsenic was found to be electrically inactive. Rapid quenching of this material resulted in larger carrier concentrations and a better correlation with crystal growth parameters. Distribution coefficients were calculated from the electrical measurements on antimony‐doped crystals grown by a solvent evaporation technique. No significant ``facet effect'' was observed for these crystals. Reflectivity measurements between 2 and 24 μ were used to deduce the electron effective mass as a function of carrier concentration. In the carrier concentration range studied (up to 8×1019 cm−3), the effective mass increases only slightly and is independent of the specific dopant. The free carrier absorption is dependent on dopant. The absorption and electrical data are correlated by using elementary conduction theory.
98 citations
TL;DR: In this paper, the authors investigated nonequilibrium properties of the single impurity Anderson model by means of the functional renormalization group (fRG) within Keldysh formalism.
Abstract: We investigate nonequilibrium properties of the single impurity Anderson model by means of the functional renormalization group (fRG) within Keldysh formalism. We present how the level broadening Γ/2 can be used as flow parameter for the fRG. This choice preserves importan t aspects of the Fermi liquid behaviour that the model exhibits in case of particle-hole symmetry. An approximation scheme for the Keldysh fRG is developed which accounts for the frequency dependence of the two-particle vertex in a way similar but not equivalent to a recently published approximation to the equilibrium Matsubara fRG. Our method turns out to be a flexible tool for the study of weak to intermediate on-site interactions U . 3Γ. In equilibrium we find excellent agreement with NRG results for the linear conductance at finite gate vol tage, magnetic field, and temperature. In nonequilibrium, our results for the current agree well with TD-DMRG. For the nonlinear conductance as function of the bias voltage, we propose reliable results at finite magne tic field and finite temperature. Furthermore, we demonstrate the exponentially small scale of the Kondo temperature to appear in the second order derivative of the self-energy. We show that the approximation is, however, not able to reproduce the scaling of the effective mass at large interactions.
98 citations
TL;DR: In this paper, zero and finite temperature contributions of ground state correlations to the nuclear mean field are studied in nuclear matter at normal density, where the framework is the nonrelativistic hole line expansion with the Paris potential as the bare NN interaction.
98 citations
TL;DR: In this article, the authors developed a detailed theory of the tunneling event in the presence of phonons, which generalizes the traditional methods (truncating the energy spectrum of the defect, treating it as a discrete "spin" system) which are valid only in the weakly coupled low-mass regime.
Abstract: We have found a new method for dealing with phonon modes in path integrals. Using it and an instanton calculation, we have developed a detailed theory of the tunneling event in the presence of phonons. This theory generalizes the traditional methods (truncating the energy spectrum of the defect, treating it as a discrete "spin" system) which are valid only in the weakly coupled low-mass regime. Most atomic tunneling will be described by an "effective mass" for the defect due to coupled lattice motion; we use (KCl:${\mathrm{Li}}^{+}$) as an example of this "slow-flip" regime. A physical picture describing electrons which are strongly coupled to phonon modes (i.e., self-trapped and polaronic electrons) is presented, but the instanton machinery does not simplify in this regime and direct calculation is necessary. We present a study of Anderson's negative-$U$ centers to elucidate this type of tunneling. We also use a two-parameter model to distinguish the domains of validity for the truncation, self-trapped, and effective-mass regimes.
98 citations