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61.
A.A. Zvyagin 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):351-360
The behavior of charge and spin persistent currents in an integrable lattice ring of strongly correlated electrons with a
magnetic impurity is exactly studied. Our results manifest that the oscillations of charge and spin persistent currents are
similar to the ones, earlier obtained for integrable continuum models with a magnetic impurity. The difference is due to two
(instead of one) Fermi velocities of low-lying excitations. The form of oscillations in the ground state is “saw-tooth”-like,
generic for any multi-particle coherent one-dimensional models. The integrable magnetic impurity introduces net charge and
spin chiralities in the generic integrable lattice system, which determine the initial phase shifts of charge and spin persistent
currents. We show that the magnitude of the charge persistent current in the generic Kondo situation does not depend on the
parameters of the magnetic impurity, unlike the (magneto)resistivity of transport currents.
Received 30 January 2003 / Received in final form 12 March 2003 Published online 11 April 2003
RID="a"
ID="a"e-mail: zvyagin@fy.chalmers.se 相似文献
62.
We consider a general system of n noninteracting identical particles which evolve under a given dynamical law and whose initial microstates are a priori independent. The time evolution of the n-particle average of a bounded function on the particle microstates is then examined in the large-n limit. Using the theory of large deviations, we show that if the initial macroscopic average is constrained to be near a given value, y, then the macroscopic average at time t converges in probability as n to a value
t(y) given explicitly in terms of a canonical expectation. Some general features of the graph of
t(y) versus t are examined, particularly in regard to continuity, symmetry, and convergence. 相似文献
63.
Based on the 1/n-expansion derived in a previous paper, the displacement fluctuations are analyzed in a quantum n-vector model of anharmonic crystal in the large n regime. It is shown that in the ferroelectric phase the n limit of the local fluctuation field has faster large-distance correlation decay than its Hartree–Fock approximation. Also, the critical exponent of the global displacement fluctuation is strictly smaller there than the Hartree–Fock exponent. In particular, the displacement fluctuations may be normal in the ferroelectric phase in spite of the Hartree–Fock prediction. 相似文献
64.
Yuri Kozitsky 《Letters in Mathematical Physics》2000,53(4):289-303
A lattice model of N-dimensional quantum anharmonic oscillators with a polynomial anharmonicity and a ferroelectric pair interaction is considered. For arbitrary N
, correlation inequalities, showing that the temperature Green functions of this model are dominated by the corresponding Green functions of the scalar (N=1) model, are proven. These inequalities are then used to prove that the fluctuations of displacements of particles remain normal at all temperatures provided the model parameters obey a certain condition. In particular this means that the smallest distance between the energy levels of the corresponding one-dimensional isolated oscillator should be large enough or its mass should be small enough. 相似文献
65.
Fluctuations of the semiconductor surface potential in a Si-SiO2 structure, caused by irradiation with different high-energy particles (50 MeV electrons and 40 keV arsenic ions) and subsequent annealing, have been studied by measuring the semiconductor interface state parameters. It is established that the fluctuation of the semiconductor surface potential decreases slightly, from 0.049 V to 0.044 V, after irradiation, while a considerable increase is observed after annealing. For the samples irradiated by arsenic ions, the increase in fluctuation is much larger (0.096 V) than that for the electron-irradiated samples (0.06 V). 相似文献
66.
A.-J. Li C.-L. Wang L. Wang J.-H. Wu J.-Y. Gao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):373-379
We investigate the spontaneously generated coherence (SGC) in a Doppler broadened four-level atomic system driven by two coherent
fields. We plot
the spontaneous emission spectra with different parameters and discuss how
the initial atomic conditions and parameters of both fields change the
number of peaks and dark lines of spontaneous emission spectra. Furthermore, we also show how the spontaneous emission spectrum
is modified by
Doppler effects in the viewed direction. Our results have important
references to the experimental observation of SGC in hot atomic vapors. 相似文献
67.
SiC/SiO2 nanocomposite coating was deposited by electron beam-physical vapor deposition (EB-PVD) through depositing SiC target on pre-oxidized 316 stainless steel (SS) substrate. High melting point component C remained and covered on the surface of ingot after evaporation. When SiC ingot was reused, remaining C had an effect on the composition, hardness and emissivity of SiC/SiO2 nanocomposite coating. The composition of ingot and coating was studied by X-ray photoelectron spectroscopy (XPS). The influence of remaining C on hardness and spectral normal emissivity of SiC/SiO2 nanocomposite coating was investigated by nanoindentation and Fourier transform infrared spectrum (FTIR), respectively. The results show that remaining C has a large effect on hardness and a minor effect on spectral normal emissivity of SiC/SiO2 nanocomposite coating. 相似文献
68.
We generalize the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji (the DDC formalism) in the fourth order for two atoms in interaction with scalar fields in vacuum to a thermal bath at finite temperature T, and then calculate the interatomic interaction energy of two ground-state atoms separately in terms of the contributions of thermal fluctuations and the radiation reaction of the atoms and analyze in detail the thermal corrections to the van der Waals and Casimir–Polder interactions. We discover a particular region, i.e. $\sqrt[4]{{\lambda }^{3}\beta }\ll L\ll \lambda $ with L, β and λ denoting the interatomic separation, the wavelength of thermal photons and the transition wavelength of the atoms respectively, where the thermal corrections remarkably render the van der Waals force, which is usually attractive, repulsive, leading to an interesting crossover phenomenon of the interatomic interaction from attractive to repulsive as the temperature increases. We also find that the thermal corrections cause significant changes to the Casimir–Polder force when the temperature is sufficiently high, resulting in an attractive force proportional to TL−3 in the λ ≪ β ≪ L region, and a force that can be either attractive or repulsive and even vanishing in the β ≪ λ ≪ L region depending on the interatomic separation. 相似文献
69.
If gravity is quantized, one of the consequences may be that the spacetime coordinates are quantized and become noncommutative. The κ-Minkowski spacetime is such kind of noncommutative spacetime. In this paper, the resonance interaction energy of a two-atom system coupled with a fluctuating vacuum scalar field in the κ-Minkowski spacetime is studied. It is found that the resonance interaction energy is dependent on the interatomic separation, the transition wavelength of the atoms, and the spacetime non-commutativity. When the interatomic separation is small compared with a characteristic length determined by the spacetime non-commutativity parameter and the transition wavelength, the resonance interaction energy is that in the Minkowski spacetime plus a correction due to the spacetime non-commutativity. When the interatomic separation is comparable to or larger than the characteristic length, the resonance interaction energy cannot be organized in the form of a Minkowski term plus a correction, which indicates that the long-range behavior of the vacuum in the κ-Minkowski spacetime is fundamentally different from that in the Minkowski spacetime. 相似文献
70.
F. F. Maia Jr. J. A. K. Freire G. A. Farias V. N. Freire E. F. da Silva Jr. 《Applied Surface Science》2002,190(1-4):247-251
The excitonic properties of a ZnSe/ZnSxSe1−x strained quantum well (QW) are calculated taking into account interface effects. Numerical results obtained with ZnS0.18Se0.82/ZnSe QWs show that graded interfaces can be responsible for a strong broadening of excitonic spectra. 相似文献