84 research outputs found
Medida Rápida e Simultânea dos Tempos de Relaxação Longitudinal e Transversal por RMN-CWFP.
bitstream/CNPDIA/10475/1/CT66_2005.pd
Nonanalytic corrections to the specific heat of a three-dimensional Fermi liquid
We revisit the issue of the leading nonanalytic corrections to the
temperature dependence of the specific heat coefficient,
for a system of interacting fermions in three dimensions. We show that the
leading temperature dependence of the specific heat coefficient comes from two physically distinct processes.
The first process involves a thermal excitation of a single particle-hole pair,
whose components interact via a nonanalytic dynamic vertex. The second process
involves an excitation of three particle-hole pairs which interact via the
analytic static fixed-point vertex. We show that the single-pair contribution
is expressed via the backscattering amplitude of quasiparticles at the Fermi
surface. The three-pair contribution does not have a simple expression in terms
of scattering in particular directions. We clarify the relation between these
results and previous literature on both 3D and 2D systems, and discuss the
relation between the nonanalyticities in and those in spin
susceptibilities
Electron-phonon renormalization in small Fermi energy systems
The puzzling features of recent photoemission data in cuprates have been
object of several analysis in order to identity the nature of the underlying
electron-boson interaction. In this paper we point out that many basilar
assumptions of the conventional analysis as expected to fail in small Fermi
energy systems when, as the cuprates, the Fermi energy is
comparable with the boson energy scale. We discuss in details the novel
features appearing in the self-energy of small Fermi energy systems and the
possible implications on the ARPES data in cuprates.Comment: 4 pages, 5 eps figures include
Avelumab in European patients (pts) with metastatic Merkel cell carcinoma (mMCC): Experience from an ad-hoc expanded access program (EAP)
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Temperature dependence of the collective mode and its influence on the band splitting in bilayer cuprates
The recently observed bilayer splitting in high-T cuprates is analyzed
within a model where the charge carriers are coupled to a phenomenological
bosonic spectrum which interpolates between the marginal Fermi liquid structure
and collective mode type behavior as a function of temperature. We argue that
the origin of the collective mode is probably associated with dynamic
incommensurate charge density waves. Moreover it is shown that the resulting
temperature dependence of the self-energy is in good agreement with
as extracted from angle-resolved photoemission data.Comment: 6 pages, 4 figures, accepted for PR
Quantum Oscillations of Electrons and of Composite Fermions in Two Dimensions: Beyond the Luttinger Expansion
Quantum oscillation phenomena, in conventional 2-dimensional electron systems
and in the fractional quantum Hall effect, are usually treated in the
Lifshitz-Kosevich formalism. This is justified in three dimensions by
Luttinger's expansion, in the parameter . We show that in two
dimensions this expansion breaks down, and derive a new expression, exact in
the limit where rainbow graphs dominate the self-energy. Application of our
results to the fractional quantum Hall effect near half-filling shows very
strong deviations from Lifshitz-Kosevich behaviour. We expect that such
deviations will be important in any strongly-interacting 2-dimensional
electronic system.Comment: 4 pages, 3 figures, LaTe
Collective Modes and the Superconducting State Spectral Function of Bi2212
Photoemission spectra of the high temperature superconductor Bi2212 near
(pi,0) show a dramatic change when cooling below Tc: the broad peak in the
normal state turns into a sharp low energy peak followed by a higher binding
energy hump. Recent experiments find that this low energy peak persists over a
significant range in momentum space. We show in this paper that these data are
well described by a simple model of electrons interacting with a collective
mode which appears only below Tc.Comment: 4 pages, revtex, 4 encapsulated postscript figure
Perturbation theory of the dynamic inverse spin Hall effect with charge conservation
We present gauge-invariant theory of the dynamic inverse spin Hall effect
driven by the spin--orbit interaction in metallic systems. Charge conservation
is imposed diagrammatically by including vertex corrections. We show the charge
current is induced by an effective electric field that is proportional to the
spin current pumped by the magnetization dynamics. The result is consistent
with recent experiments.Comment: 16pages, 5figure
A Vertex Correction in the Gap Equation for the High Temperature Superconductors
We show that the Migdal theorem is obviously violated in the high Tc cuprates
and the vertex correction should be included, in particular, in the gap
equation, in order to be consistent with the anomalously strong inelastic
scattering in the ``hot spots'', which is observed from the various normal
state experiments. The vertex correction is obtained by utilizing the
generalized Ward identity, which is shown to hold in the important scattering
channel for the pairing interaction in the high Tc cuprates. As a result, we
find a strong enhancement of Tc from the vertex correction despite of the
strong pair breaking effect due to the inelastic scattering.Comment: 5 pages, 2 figure
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