scholarly journals ANTIFERROMAGNETISM, STRIPES, AND SUPERCONDUCTIVITY IN THE t–J MODEL WITH COULOMB INTERACTION

2001 ◽  
Vol 15 (08) ◽  
pp. 1117-1126 ◽  
Author(s):  
JUNGHOON HAN ◽  
QIANG-HUA WANG ◽  
DUNG-HAI LEE
Keyword(s):  
Long Range ◽  
Coulomb Interaction ◽  
Lower Energy ◽  
Mean Field ◽  
Doping Density ◽  
Stripe Width ◽  
The Mean ◽  
D Wave

We study mean-field phases of the t–J model with long-range Coulomb interaction. In the order of increasing doping density we find a classical antiferromagnet, charge and spin stripes, and a uniform d-wave superconductor, at the realistic doping parameters. Both in-phase and anti-phase stripes exist as metastable configurations, but the in-phase stripes have a slightly lower energy. The dependence of the stripe width and the inter-stripe spacing on the doping is examined. Effects of fluctuations around the mean-field states are discussed.

SIMPLE ATTEMPT TO OBSERVE SUPERCONDUCTIVITY ON ANTIFERROMAGNETIC BACKGROUND IN THE t-J MODEL

1992 ◽  
Vol 06 (20) ◽  
pp. 3327-3340 ◽  
Author(s):  
PAVOL KALINAY
Keyword(s):  
Long Range ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Long Range Order ◽  
Wave Symmetry ◽  
The Mean ◽  
Hubbard Operators ◽  
Superconductive Phase ◽  
D Wave

Having treated the t-J Hamiltonian in the mean-field approximation on basis generated by the Hubbard operators [Formula: see text], we tried to find the superconductive phase on the antiferromagnetic background. The pairing of the d-wave symmetry appeared to coexist well with the AF long-range order.

scholarly journals Evidence of exactness of the mean-field theory in the nonextensive regime of long-range classical spin models

2000 ◽  
Vol 61 (17) ◽  
pp. 11521-11528 ◽  
Author(s):  
Sergio A. Cannas ◽  
A. C. N. de Magalhães ◽  
Francisco A. Tamarit
Keyword(s):  
Field Theory ◽  
Long Range ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spin Models ◽  
Classical Spin ◽  
The Mean ◽  
Classical Spin Models

THERMODYNAMICS OF THE FERMI-LINEARIZED EXTENDED HUBBARD MODEL

1992 ◽  
Vol 06 (22) ◽  
pp. 3529-3541 ◽  
Author(s):  
ANDREA DANANI ◽  
ARIANNA MONTORSI ◽  
MARIO RASETTI
Keyword(s):  
Hubbard Model ◽  
Coulomb Interaction ◽  
Mean Field ◽  
Local Magnetic Moment ◽  
The Novel ◽  
Extended Hubbard Model ◽  
Site Cluster ◽  
The Mean ◽  
Two Phases

The fermi linearization scheme for a two-site cluster (dimer) is applied to the extended Hubbard model, including Coulomb interaction between nearest neighbour sites. The partition function and the order parameter, as well as the average double-occupation and local magnetic moment are evaluated. The theory is checked by extended numerical analysis, performed here in the homogeneous case, when pairing is zero, and deriving the explicit temperature and filling dependence of the above quantities. An interesting feature that emerges from such calculations is that the mean-field parameter characteristic of fermi-linearization is capable of describing two different phases, one of which is not present in the conventional Hubbard model. The order parameters corresponding to the two phases are explicitly derived. The novel phase can be ascribed to the n.n. Coulomb interaction, the role of whose strength V is analysed.

scholarly journals Supersolids of Hard Core - Bosons on a Triangular Lattice

2011 ◽  
Vol 21 (4) ◽  
pp. 301
Author(s):  
Nguyen Toan Thang ◽  
Pham Thi Thanh Nga
Keyword(s):  
Long Range ◽  
Triangular Lattice ◽  
Mean Field Theory ◽  
Mean Field ◽  
Hard Core ◽  
Xxz Model ◽  
Supersolid Phase ◽  
The Mean ◽  
Boson Model ◽  
Broad Region

We study the boson model on a triangular lattice interacting only via on-site hardcore repulsion by mapping to a system of spins $(S = 1/2)$. We investigate the supersolid phase of the systems which is a state matter displaying both diagonal long- range (solid) order as well as off-diagonal long-range (superfluidity) by utilizing a semionic representation for the spin-XXZ model. We show that the supersolid order is stable in the mean-field theory for a broad region of parameters. The inclusion of spin wave corrections modifies this picture, but the supersolid phase is still quite robust on the triangular lattices.

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