scholarly journals Periodic ordering of clusters and stripes in a two-dimensional lattice model. I. Ground state, mean-field phase diagram and structure of the disordered phases

2014 ◽  
Vol 140 (11) ◽  
pp. 114701 ◽  
Author(s):  
J. Pȩkalski ◽  
A. Ciach ◽  
N. G. Almarza
Keyword(s):  
Phase Diagram ◽  
Ground State ◽  
Lattice Model ◽  
Mean Field ◽  
Two Dimensional ◽  
Field Phase ◽  
Dimensional Lattice

scholarly journals Mean-field Solution of the mixed spin-1 and spin-5/2Ising system with different single-ion anisotropies

2009 ◽  
Vol 6 (4) ◽  
pp. 784-789
Author(s):  
Baghdad Science Journal
Keyword(s):  
Phase Diagram ◽  
Ground State ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Two Dimensional ◽  
Ground State Phase Diagram ◽  
Mixed Spin ◽  
Bogoliubov Inequality ◽  
The Mean

The mixed-spin ferrimagnetic Ising system consists of two-dimensional sublattices A and B with spin values and respectively .By used the mean-field approximation MFA of Ising model to find magnetism( ).In order to determined the best stabile magnetism , Gibbs free energy employ a variational method based on the Bogoliubov inequality .The ground-state (Phase diagram) structure of our system can easily be determined at , we find six phases with different spins values depend on the effect of a single-ion anisotropies .these lead to determined the second , first orders transition ,and the tricritical points as well as the compensation phenomenon .

Phase diagram of a two-dimensional lattice-gas model of oxygen ordering inYBa2Cu3Ozwith realistic interactions

1995 ◽  
Vol 52 (13) ◽  
pp. 9784-9792 ◽  
Author(s):  
D. J. Liu ◽  
T. L. Einstein ◽  
P. A. Sterne ◽  
L. T. Wille
Keyword(s):  
Phase Diagram ◽  
Lattice Gas ◽  
Lattice Gas Model ◽  
Two Dimensional ◽  
Dimensional Lattice ◽  
Oxygen Ordering

HIGH FIELD PHASE DIAGRAM OF THE FIELD-INDUCED SUPERCONDUCTING STATE OF λ-(BETS)2FeCl4

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3101-3104
Author(s):  
L. BALICAS ◽  
J. S. BROOKS ◽  
K. STORR ◽  
S. UJI ◽  
M. TOKUMOTO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Superconducting State ◽  
Ground State ◽  
Electrical Transport ◽  
High Field ◽  
Two Dimensional ◽  
Exchange Field ◽  
Organic Conductor ◽  
Field Phase ◽  
Antiferromagnetic Ground State

We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor λ- (BETS) 2 FeCl 4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T, and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe 3+ ions. We further argue that the Fe 3+ moments are essential to stabilize the resulting singlet, two-dimensional superconducting state. Here we provide experimental evidence indicating that this state, as well as the insulating antiferromagnetic ground state, is extremely sensitive to hydrostatic pressure.

Mean-field phase diagram of cold lattice bosons in disordered potentials

2007 ◽  
Vol 76 (1) ◽  
Author(s):  
P. Buonsante ◽  
V. Penna ◽  
A. Vezzani ◽  
P. B. Blakie
Keyword(s):  
Phase Diagram ◽  
Mean Field ◽  
Field Phase

Simulations of Polarization Reversals by a Two-Dimensional Lattice Model

1992 ◽  
Vol 31 (Part 1, No. 9B) ◽  
pp. 3238-3240 ◽  
Author(s):  
Masayoshi Omura ◽  
Hideo Adachi ◽  
Yoshihiro Ishibashi
Keyword(s):  
Lattice Model ◽  
Two Dimensional ◽  
Dimensional Lattice

η-PAIRING SUPERCONDUCTIVITY IN THE NEGATIVE-U HUBBARD MODEL: EFFECT OF FLUCTUATIONS AND DISORDER

1994 ◽  
Vol 08 (15) ◽  
pp. 2041-2058
Author(s):  
JÜRGEN STEIN
Keyword(s):  
Phase Diagram ◽  
Asymptotic Expansion ◽  
Hubbard Model ◽  
Strong Coupling ◽  
Mean Field ◽  
Higher Order ◽  
Field Phase ◽  
Effective Pair ◽  
The Mean ◽  
Pair Hopping

We have studied the influence of singular fluctuations around the mean-field solution as well as higher order contributions to the geometry controlled asymptotic expansion of the propagators on η-pairing superconductivity in the strong coupling negative-U Hubbard model in the presence of unpaired electrons. The modifications of the mean-field results due to the introduction of disorder and allowance for finite U are also calculated. Besides the singularities already present in the O(2) nonlinear σ-model we find a filling-depending singular depression of the repulsive effective pair-hopping interaction which strongly alters the mean-field phase diagram and appears to suppress the η-pairing phase near the band edges.

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