共查询到20条相似文献,搜索用时 15 毫秒
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J. Zittartz 《Zeitschrift für Physik B Condensed Matter》1976,23(1):55-62
The two dimensional classicalXY-model, representative for two dimensional models with continuous symmetry, is shown to undergo a phase transition of continuous order in a low temperature region. In particular: 1. The correlation functions decay with a power law at large distance in a temperature range belowT′ with a characteristic singular exponentη which varies continuously between 0 and ∞; 2. For magnetic fieldB → 0 the free energy develops a singular part in the form of a power with a singular exponentκ which varies continuously between 1 and ∞ atT ∞ (<T′); 3. The singular exponentsκ, η, and a correlation length exponent are related to one another by scaling laws and are determined by a dispersion coefficient for low lying excitations. 相似文献
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We construct a local interacting quantum dimer model on the square lattice, whose zero-temperature phase diagram is characterized by a line of critical points separating two ordered phases of the valence bond crystal type. On one side, the line of critical points terminates in a quantum transition inherited from a Kosterlitz-Thouless transition in an associated classical model. We also discuss the effect of a longer-range dimer interaction that can be used to suppress the line of critical points by gradually shrinking it to a single point. Finally, we propose a way to generalize the quantum Hamiltonian to a dilute dimer model in presence of monomers and we qualitatively discuss the phase diagram. 相似文献
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A one-dimensional reaction-diffusion model consisting of two species of particles and vacancies on a ring is introduced. The number of particles in one species is conserved while in the other species it can fluctuate because of creation and annihilation of particles. It has been shown that the model undergoes a continuous phase transition from a phase where the currents of different species of particles are equal to another phase in which they are different. The total density of particles and also their currents in each phase are calculated exactly. 相似文献
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《Physics letters. A》1996,223(4):261-266
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A. Alastuey 《Physics letters. A》1980,76(2):134-136
The melting curve of the two-dimensional electron system is interpolated between the known classical and ground state limits. The coexistence curve encloses a finite solid-phase domain, as in the three-dimensional case. 相似文献
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The ground-state phase diagram of a two-dimensional Bose system with dipole-dipole interactions is studied by means of a quantum Monte Carlo technique. Our calculation predicts a quantum phase transition from a gas to a solid phase when the density increases. In the gas phase, the condensate fraction is calculated as a function of the density. Using the Feynman approximation, the collective excitation branch is studied and the appearance of a roton minimum is observed. The results of the static structure factor at both sides of the gas-solid phase are also presented. The Lindemann ratio at the transition point becomes gamma=0.230(6). The condensate fraction in the gas phase is estimated as a function of the density. 相似文献
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V. N. Gheorghe 《Applied physics. B, Lasers and optics》1985,38(3):205-207
Abtract The study deals with the ground-state energy transition of a multicomponent atomic system from its normal state to the superradiant state when interacting with a multimode quantized electromagnetic field. The threshold conditions are determined.Alexander-von-Humboldt awardee 相似文献
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Triplet-Excitons in a mixed 1 : 1 anthracene—tetracyanobenzene single crystal are established by ESR-spectrocopy. These excitons (lifetime 0.5 msec) are characterized by a hopping frequency of v = 1.3 × 106 K at 300K. The temperature dependence of the ESR line shape indicates a phase transition of the crystal at Tt = 205K. Above and below the phase transition the exciton mobility is nearly temperature independent. 相似文献
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A diffusion anomaly in dipole-oriented two-dimensional excitons in GaAs/AlGaAs coupled quantum wells
Il Nuovo Cimento D - We have observed an anomaly in the low-temperature photoluminescence of dipole-oriented long-lived excitons in a coupled quantum well under an electrical bias. A discrepancy... 相似文献
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Metal balls with a diameter of 1.59 mm, gently rubbed against a dielectric surface using a shaker, are seen to spontaneously exhibit a two-dimensional liquidlike order with macroscopic dimensions, viz., interball distances of several millimeters. This liquidlike order transforms to a gaslike order through coexistence upon decreasing the area fraction of the balls. The measured pair interaction of like-charged balls surprisingly exhibits a long-range attractive term analogous to that in charged colloids. 相似文献
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A. V. Gorbunov L. V. Kulik V. A. Kuznetsov A. S. Zhuravlev A. V. Larionov V. B. Timofeev I. V. Kukushkin 《JETP Letters》2017,105(10):682-685
A modified-gravity theory with a four-form field strength F, a variable gravitational coupling parameter G(F), and a standard matter action are considered here. Maxwell and Einstein equations are now derived when including to action also derivates of F. The energy momentum tensor of the 4-form field contains both the part, which is typical for the fundamental (pseudo)scalar, and the part, which cancels the divergent contribution of the zero-point energies of quantum fields to the vacuum energy and thus leads to the natural nullification of the cosmological constant in Minkowski vacuum. 相似文献
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Phase transition in a two-dimensional Ising ferromagnet based on the generalized zero-temperature Glauber dynamics 下载免费PDF全文
At zero temperature, based on the Ising model, the phase transition in a two-dimensional square lattice is studied using the generalized zero-temperature Glauber dynamics. Using Monte Carlo (MC) renormalization group methods, the static critical exponents and the dynamic exponent are studied; the type of phase transition is found to be of the first order. 相似文献
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The conditions for spontaneous spin polarization in a two-dimensional system in a zero magnetic field are considered in the case of a partial filling of the lower quantum-well subbands when the energy of exchange interaction of charge carriers exceeds their kinetic energy. The critical density above which the two-dimensional gas of charge carriers undergoes complete spin depolarization is determined in the Hartree-Fock approximation. It is assumed that this process can be due to a transition of the two-dimensional gas to a metallic state. 相似文献