260,378 research outputs found
Role of bulk and surface phonons in the decay of metal surface states
We present a comprehensive theoretical investigation of the electron-phonon
contribution to the lifetime broadening of the surface states on Cu(111) and
Ag(111), in comparison with high-resolution photoemission results. The
calculations, including electron and phonon states of the bulk and the surface,
resolve the relative importance of the Rayleigh mode, being dominant for the
lifetime at small hole binding energies. Including the electron-electron
interaction, the theoretical results are in excellent agreement with the
measured binding energy and temperature dependent lifetime broadening.Comment: 4 pages, 3 figure
The electron lifetime in Luttinger liquids
We investigate the decoherence of the electron wavepacket in purely ballistic
one-dimensional systems described through the Luttinger liquid (LL). At a
finite temperature and long times , we show that the electron Green's
function for a fixed wavevector close to one Fermi point decays as
, as opposed to the power-law behavior occurring at short
times, and the emerging electron lifetime obeys for
spinful as well as spinless electrons. For strong interactions, , reflecting that the electron is not a good Landau quasiparticle in LLs. We
justify that fractionalization is the main source of electron decoherence for
spinful as well as spinless electrons clarifying the peculiar electron mass
renormalization close to the Fermi points. For spinless electrons and weak
interactions, our intuition can be enriched through a diagrammatic approach or
Fermi Golden rule and through a Johnson-Nyquist noise picture. We stress that
the electron lifetime (and the fractional quasiparticles) can be revealed from
Aharonov-Bohm experiments or momentum resolved tunneling. We aim to compare the
results with those of spin-incoherent and chiral LLs.Comment: 20 pages, 1 column, 6 figures, 1 Table; expands cond-mat/0110307 and
cond-mat/0503652; final version to appear in PR
Many-body Effects in Angle-resolved Photoemission: Quasiparticle Energy and Lifetime of a Mo(110) Surface State
In a high-resolution photoemission study of a Mo(110) surface state various
contributions to the measured width and energy of the quasiparticle peak are
investigated. Electron-phonon coupling, electron-electron interactions and
scattering from defects are all identified mechanisms responsible for the
finite lifetime of a valence photo-hole. The electron-phonon induced mass
enhancement and rapid change of the photo-hole lifetime near the Fermi level
are observed for the first time.Comment: RevTEX, 4 pages, 4 figures, to be published in PR
Spin dynamics of electrons in the first excited subband of a high-mobility low-density 2D electron system
We report on time-resolved Kerr rotation measurements of spin coherence of
electrons in the first excited subband of a high-mobility low-density
two-dimensional electron system in a GaAs/Al0.35Ga0.65As heterostructure. While
the transverse spin lifetime (T2*) of electrons decreases monotonically with
increasing magnetic field, it has a non-monotonic dependence on the
temperature, with a peak value of 596 ps at 36 K, indicating the effect of
inter-subband electron-electron scattering on the electron spin relaxation. The
spin lifetime may be long enough for potential device application with
electrons in excited subbands
Experimental tests on the lifetime Asymmetry
The experimental test problem of the left-right polarization-dependent
lifetime asymmetry is discussed. It shows that the existing experiments cannot
demonstrate the lifetime asymmetry to be right or wrong after analyzing the
measurements on the neutron, the muon and the tau lifetime, as well as the
experiment. However, It is pointed out emphatically that the SLD and the
E158 experiments, the measurements of the left-right integrated cross section
asymmetry in boson production by collisions and by
electron-electron M{\o}ller scattering, can indirectly demonstrate the lifetime
asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose
some possible experiments on the decays of polarized muons. The precise
measurement of the lifetime asymmetry could have important significance for
building a muon collider, also in cosmology and astrophysics. It would provide
a sensitive test of the standard model in particle physics and allow for
exploration of the possible interactions.Comment: 11 pages, 1 figur
Reentrance effect in a graphene n-p-n junction coupled to a superconductor
We study the interplay of Klein tunneling (= interband tunneling) between
n-doped and p-doped regions in graphene and Andreev reflection (= electron-hole
conversion) at a superconducting electrode. The tunneling conductance of an
n-p-n junction initially increases upon lowering the temperature, while the
coherence time of the electron-hole pairs is still less than their lifetime,
but then drops back again when the coherence time exceeds the lifetime. This
reentrance effect, known from diffusive conductors and ballistic quantum dots,
provides a method to detect phase coherent Klein tunneling of electron-hole
pairs.Comment: 4 pages, 3 figure
Theory of Luminescent Emission in Nanocrystal ZnS:Mn with an Extra Electron
We consider the effect of an extra electron injected into a doped quantum dot
. The Coulomb interaction and the exchange interaction between the
extra electron and the states of the Mn ion will mix the wavefunctions, split
the impurity energy levels, break the previous selection rules and change the
transition probabilities. Using this model of an extra electron in the doped
quantum dot, we calculated the energy and the wavefunctions, the luminescence
probability and the transition lifetime and compare with the experiments. Our
calculation shows that two orders of magnitudes of lifetime shortening can
occur in the transition when an extra electron is present.Comment: 15 pages, 2 Figs No change in Fig
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