scholarly journals Underdoped cuprate phenomenology in the two-dimensional Hubbard model within the composite operator method

2007 ◽  
Vol 75 (13) ◽  
Author(s):  
Adolfo Avella ◽  
Ferdinando Mancini
Keyword(s):  
Hubbard Model ◽  
Operator Method ◽  
Composite Operator ◽  
Two Dimensional ◽  
Composite Operator Method

SCBA within composite operator method for the Hubbard model

2005 ◽  
Vol 359-361 ◽  
pp. 666-668 ◽  
Author(s):  
S. Krivenko ◽  
A. Avella ◽  
F. Mancini ◽  
N. Plakida
Keyword(s):  
Hubbard Model ◽  
Operator Method ◽  
Composite Operator ◽  
Composite Operator Method

ANALYSIS OF THE TWO-DIMENSIONAL NEGATIVE-U HUBBARD MODEL BY COMPOSITE OPERATOR METHOD

1996 ◽  
Vol 10 (22) ◽  
pp. 2745-2756 ◽  
Author(s):  
T. DI MATTEO ◽  
F. MANCINI ◽  
S. MARRA ◽  
H. MATSUMOTO
Keyword(s):  
Hubbard Model ◽  
Chemical Potential ◽  
Particle Density ◽  
Mean Field ◽  
Finite Size ◽  
Operator Method ◽  
Field Approximation ◽  
Composite Operator ◽  
Mean Field Approximation ◽  
Two Dimensional

The two-dimensional negative-U Hubbard model is studied by means of the composite operator approach. In a generalized mean-field approximation we calculate different quantities, as the chemical potential, the double occupancy, the static uniform spin magnetic susceptibility and the density of states for various values of the particle density, attractive on-site interaction and temperature. Comparison with the results obtained by numerical analysis on finite size lattices shows a good agreement.

scholarly journals Composite Operator Method Analysis of the Underdoped Cuprates Puzzle

2014 ◽  
Vol 2014 ◽  
pp. 1-29 ◽  
Author(s):  
Adolfo Avella
Keyword(s):  
Fermi Surface ◽  
Hubbard Model ◽  
Cuprate Superconductors ◽  
Operator Method ◽  
Coulomb Repulsion ◽  
Pauli Principle ◽  
Composite Operator ◽  
Antiferromagnetic Correlations ◽  
Underdoped Cuprates ◽  
Composite Operator Method

The microscopical analysis of the unconventional and puzzling physics of the underdoped cuprates, as carried out lately by means of the composite operator method (COM) applied to the 2D Hubbard model, is reviewed and systematized. The 2D Hubbard model has been adopted as it has been considered the minimal model capable of describing the most peculiar features of cuprates held responsible for their anomalous behavior. COM is designed to endorse, since its foundation, the systematic emergence in any SCS of new elementary excitations described by composite operators obeying noncanonical algebras. In this case (underdoped cuprates—2D Hubbard model), the residual interactions—beyond a 2-pole approximation—between the new elementary electronic excitations, dictated by the strong local Coulomb repulsion and well described by the two Hubbard composite operators, have been treated within the noncrossing approximation. Given this recipe and exploiting the few unknowns to enforce the Pauli principle content in the solution, it is possible to qualitatively describe some of the anomalous features of high-Tc cuprate superconductors such as large versus small Fermi surface dichotomy, Fermi surface deconstruction (appearance of Fermi arcs), nodal versus antinodal physics, pseudogap(s), and kinks in the electronic dispersion. The resulting scenario envisages a smooth crossover between an ordinary weakly interacting metal sustaining weak, short-range antiferromagnetic correlations in the overdoped regime to an unconventional poor metal characterized by very strong, long-but-finite-range antiferromagnetic correlations leading to momentum-selective non-Fermi liquid features as well as to the opening of a pseudogap and to the striking differences between the nodal and the antinodal dynamics in the underdoped regime.

scholarly journals The 1D Hubbard model within the Composite Operator Method

2002 ◽  
Vol 29 (3) ◽  
pp. 399-417 ◽  
Author(s):  
A. Avella ◽  
F. Mancini ◽  
M.d.M. Sánchez-López
Keyword(s):  
Hubbard Model ◽  
Operator Method ◽  
Composite Operator ◽  
Composite Operator Method

scholarly journals NEW COMPARISONS FOR LOCAL QUANTITIES OF THE TWO-DIMENSIONAL HUBBARD MODEL

2003 ◽  
Vol 17 (04n06) ◽  
pp. 554-559 ◽  
Author(s):  
ADOLFO AVELLA ◽  
FERDINANDO MANCINI
Keyword(s):  
Monte Carlo ◽  
Hubbard Model ◽  
Quantum Monte Carlo ◽  
Approximation Scheme ◽  
Operator Method ◽  
Numerical Data ◽  
Two Dimensional ◽  
Double Occupancy ◽  
Half Filling ◽  
Composite Operator Method

We have compared the results of out approximation scheme, the composite operator, method, for the double occupancy and the internal energy of the two-dimensional Hubbard model with numerical data obtained by means of the Lanczos1and quantum Monte Carlo schemes.2The agreement is very good at both half-filling and away from it showing how reliable is the approximation scheme.

scholarly journals Emery vs. Hubbard model for cuprate superconductors: a composite operator method study

2013 ◽  
Vol 86 (6) ◽  
Author(s):  
Adolfo Avella ◽  
Ferdinando Mancini ◽  
Francesco Paolo Mancini ◽  
Evgeny Plekhanov
Keyword(s):  
Hubbard Model ◽  
Cuprate Superconductors ◽  
Operator Method ◽  
Composite Operator ◽  
Composite Operator Method

scholarly journals Local quantities for the 1D Hubbard model in the composite operator method

1998 ◽  
Vol 2 (2) ◽  
pp. 228-231
Author(s):  
A. Avella ◽  
F. Mancini ◽  
M. M. Sánchez ◽  
D. Villani
Keyword(s):  
Hubbard Model ◽  
Operator Method ◽  
Composite Operator ◽  
Composite Operator Method
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