ON THE VALIDITY OF MEAN-FIELD THEORY FOR ANYONS ON A LATTICE

1992 ◽  
Vol 06 (30) ◽  
pp. 1951-1960 ◽  
Author(s):  
A.A. OVCHINNIKOV ◽  
An. A. OVCHINNIKOV
Keyword(s):  
Large Deviation ◽  
Mean Field Theory ◽  
Mean Field ◽  
Hard Core ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Phase Fluctuations ◽  
Fermi Statistics ◽  
The Mean ◽  
Field Approaches

We examine the validity of the mean-field approximation for anyons on a lattice at high density. The phase fluctuations for a large deviation from the Fermi statistics, in particular for the hard core bosons, are shown to be large. The importance of the phase fluctuations in different fermionic mean-field approaches for the antiferromagnetic Heisenberg model is stressed.

scholarly journals Особенности фазовой диаграммы полужестких бозонов на квадратной решетке

2021 ◽  
Vol 63 (9) ◽  
pp. 1361
Author(s):  
В.В. Конев ◽  
Ю.Д. Панов
Keyword(s):  
Mean Field ◽  
Hard Core ◽  
Field Approximation ◽  
Charge Ordering ◽  
Mean Field Approximation ◽  
New Order ◽  
Model Parameters ◽  
Local Correlation ◽  
The Mean ◽  
Limit Form

We investigated the phase diagrams of a system of charged semi-hardcore bosons in the mean-field approximation. It is shown that an increase in the local correlation parameter leads to the transformation of the phase diagram of the system from the form characteristic of hard-core bosons to the limit form with a parabolic dependence of the critical temperature of the charge ordering on the boson concentration. The evolution between these limiting cases depends on the ratio of the model parameters and is accompanied by various effects, including a change in the type of phase transition, the appearance of new order-order transitions, and the appearance of new critical points.

MEAN-FIELD THEORY FOR LAYERED HIGH-TEMPERATURE SUPERCONDUCTORS

1988 ◽  
Vol 02 (05) ◽  
pp. 1059-1065 ◽  
Author(s):  
D. Baeriswyl ◽  
T. Schneider
Keyword(s):  
High Temperature Superconductors ◽  
Mean Field Theory ◽  
Mean Field ◽  
Three Dimensional ◽  
Interlayer Coupling ◽  
Interlayer Spacing ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Pairing Mechanism ◽  
The Mean

Using the mean-field approximation we study a model for quasi-two-dimensional layered superconductors. The interlayer coupling, assumed to be mediated by a small electron hopping term, is found to leave Tc practically unaffected. Consequently, a three-dimensional pairing mechanism is required to explain the observed dependence of Tc on the average interlayer spacing in the Bi and Tl compounds.

FRÖHLICH'S ONE-DIMENSIONAL SUPERCONDUCTOR WITH PARA-FERMI STATISTICS

1994 ◽  
Vol 08 (19) ◽  
pp. 1195-1200 ◽  
Author(s):  
V. L. SAFONOV ◽  
A. V. ROZHKOV
Keyword(s):  
Density Wave ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Wave State ◽  
One Dimensional ◽  
Fermi Statistics ◽  
The Mean ◽  
A Charge ◽  
Dimensional Crystal

The hypothesis that conduction electrons in a one-dimensional crystal obey para-Fermi statistics is discussed. Thermal properties of Fröhlich's model in the mean-field approximation are calculated within the framework of this hypothesis. It is shown that the temperature of the phase transition to a charge density wave state is greater in a system with parastatistics.

scholarly journals Calculation of the Static Properties of Local Moment Systems by the Mean Field Method

1975 ◽  
Vol 28 (6) ◽  
pp. 685 ◽  
Author(s):  
AM Stewart
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Field Approximation ◽  
Field Method ◽  
Local Moment ◽  
Mean Field Approximation ◽  
Static Properties ◽  
The Past ◽  
The Mean

It is demonstrated that two different methods which have been used in the past to calculate the static properties oflocal moment systems in the mean field approximation are incomplete. A proof is given of the correctness of another method that the author has used in several previous calculations. It is found that some exact and very general relationships exist between the conduction electron magnetization and the local moment magnetization even when it is not valid to treat the interactions between the magnetic atoms by mean field theory.

A NEW FERMION-SPIN TRANSFORMATION TO IMPLEMENT THE CHARGE-SPIN SEPARATION

1993 ◽  
Vol 07 (15) ◽  
pp. 1013-1019 ◽  
Author(s):  
SHIPING FENG ◽  
Z.B. SU ◽  
L. YU
Keyword(s):  
Mean Field ◽  
Hard Core ◽  
Field Approximation ◽  
Degree Of Freedom ◽  
Mean Field Approximation ◽  
Dimensional Case ◽  
Spinless Fermion ◽  
The Mean ◽  
Charge Degree ◽  
Good Agreement

We propose a new fermion-spin transformation to implement the charge-spin separation in the large U Hubbard, or the equivalent t-J model. The charge degree of freedom is represented by a spinless fermion while the spin degree of freedom is represented by a hard-core boson. The local constraint for single occupancy is exactly satisfied. Very good agreement with exact solution is obtained for one-dimensional case in the mean field approximation, regarding the total energy, gapless spinon and holon spectra, and the momentum distribution of physical electrons. The same approximation yields good doping dependence of the staggered magnetization in the two-dimensional case.

CAR-ORIENTED MEAN-FIELD THEORY REVISITED

2004 ◽  
Vol 18 (17) ◽  
pp. 887-894 ◽  
Author(s):  
YU-FUNG CHIEN ◽  
DING-WEI HUANG
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Critical Density ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Stochastic Noise ◽  
Collective Effect ◽  
Self Consistent ◽  
The Mean

We study the Car-Oriented Mean-Field approximation (COMF) to the Nagel–Schreckenberg model in the case of v max =3. The self-consistent equations are obtained. The solution is reached by the method of iteration. When the stochastic noise is small, the numerical simulations can be well described by the mean-field theory. When the stochastic noise is large, the flux around critical density is overestimated. The overshooting of the free flow can be attributed to the collective effect of the stochastic noise.

scholarly journals Ferrimagnetism in the Mean-Field Approximation of the Mixed Spin-3/2 and Spin-5/2 Ising System

2015 ◽  
Vol 57 ◽  
pp. 114-121 ◽  
Author(s):  
Hadey K. Mohamad
Keyword(s):  
Free Energy ◽  
Mean Field Theory ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Mixed Spin ◽  
Simple Cubic ◽  
Simple Cubic Lattice ◽  
Bogoliubov Inequality ◽  
The Mean

Using the Mean-field theory based on Bogoliubov inequality for the free energy, a ferrimagnetic mixed spin-3/2 and spin-5/2 Ising model with different anisotropies is investigated. The free energy of a mixed spin Ising ferrimagnetic system from MF approximation of the Hamiltonian is calculated. By minimizing the free energy, we obtain the equilibrium magnetizations and compensation points. In particular, we investigate the effect of a single-ion anisotropy on the magnetic properties including the compensation phenomenon, in order to clarify the characteristic behaviours in a series of molecular-based magnets . The phase diagram of the system is also discussed in the anisotropy dependence of transition temperature. Our results of this model predict the existence of many (two or three) compensation points in the ordered system on a simple cubic lattice.

MEAN-FIELD THEORY OF ANYONS NEAR BOSE STATISTICS

1994 ◽  
Vol 08 (01) ◽  
pp. 41-48
Author(s):  
JOHN MCCABE ◽  
RICHARD MACKENZIE
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Hard Core ◽  
Meissner Effect ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Bose Statistics ◽  
Domain Of Validity

We argue the validity of a mean-field approximation for a free anyon gas near Bose statistics, and show that the anyon gas can exhibit a Meissner effect in the domain of validity of the approximation only due to a hard-core repulsion.

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