260,378 research outputs found

    Role of bulk and surface phonons in the decay of metal surface states

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    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

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    We investigate the decoherence of the electron wavepacket in purely ballistic one-dimensional systems described through the Luttinger liquid (LL). At a finite temperature TT and long times tt, we show that the electron Green's function for a fixed wavevector close to one Fermi point decays as exp(t/τF)\exp(-t/\tau_F), as opposed to the power-law behavior occurring at short times, and the emerging electron lifetime obeys τF1T\tau_F^{-1}\propto T for spinful as well as spinless electrons. For strong interactions, (TτF)1(T\tau_F)\ll 1, 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

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    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

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    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

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    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 g2g-2 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 ZZ boson production by e+ee^+e^- 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 V+AV+A interactions.Comment: 11 pages, 1 figur

    Reentrance effect in a graphene n-p-n junction coupled to a superconductor

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    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

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    We consider the effect of an extra electron injected into a doped quantum dot ZnS:Mn2+ZnS:Mn^{2+}. 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 4T16A1^4T_1-^6A_1 when an extra electron is present.Comment: 15 pages, 2 Figs No change in Fig
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