Spin disorder in the two-dimensional Hubbard model: A mean-field theory

1991 ◽  
Vol 43 (7) ◽  
pp. 6216-6219 ◽  
Author(s):  
G. Vignale
Keyword(s):  
Field Theory ◽  
Hubbard Model ◽  
Mean Field Theory ◽  
Mean Field ◽  
Two Dimensional ◽  
Spin Disorder

scholarly journals Beyond extended dynamical mean-field theory: Dual boson approach to the two-dimensional extended Hubbard model

2014 ◽  
Vol 90 (23) ◽  
Author(s):  
Erik G. C. P. van Loon ◽  
Alexander I. Lichtenstein ◽  
Mikhail I. Katsnelson ◽  
Olivier Parcollet ◽  
Hartmut Hafermann
Keyword(s):  
Field Theory ◽  
Hubbard Model ◽  
Mean Field Theory ◽  
Mean Field ◽  
Dynamical Mean Field Theory ◽  
Two Dimensional ◽  
Extended Hubbard Model

COMPREHENSIVE MEAN FIELD THEORY FOR THE HUBBARD MODEL

1992 ◽  
Vol 06 (05n06) ◽  
pp. 731-747 ◽  
Author(s):  
V. JANIŠ ◽  
D. VOLLHARDT
Keyword(s):  
Field Theory ◽  
Energy Transfer ◽  
Hubbard Model ◽  
Entire Range ◽  
Mean Field Theory ◽  
Mean Field ◽  
Exact Expression ◽  
Grand Potential ◽  
Input Parameters

We derive an exact expression for the grand potential of the Hubbard model in d=∞ dimensions. By simplifying the energy transfer between up and down spins we obtain a comprehensive mean-field theory for this model. It is (i) thermodynamically consistent in the entire range of input parameters, (ii) conserving and, (iii) exact in several non-trivial limits, e. g. in the free (U→0), atomic (t→0) and Heisenberg (U≫t, n=1) limit.

scholarly journals Effect of weak disorder on the BCS–BEC crossover in a two-dimensional Fermi gas

2017 ◽  
Vol 31 (09) ◽  
pp. 1750066
Author(s):  
Ayan Khan ◽  
B. Tanatar
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Fermi Gas ◽  
Ultracold Fermi Gas ◽  
Condensate Fraction ◽  
Two Dimensional ◽  
Weak Disorder ◽  
Unique Nature

In this paper, we study the two-dimensional (2D) ultracold Fermi gas with weak impurity in the framework of mean-field theory where the impurity is introduced through Gaussian fluctuations. We have investigated the role of the impurity by studying the experimentally accessible quantities such as condensate fraction and equation of state of the ultracold systems. Our analysis reveals that at the crossover, the disorder enhances superfluidity, which we attribute to the unique nature of the unitary region and to the dimensional effect.

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