Quantum phase crossover in the spherical mean-field plus quadrupole–quadrupole and pairing model with two j-orbits

2020 ◽  
Vol 29 (06) ◽  
pp. 2050039
Author(s):  
Bo Li ◽  
Feng Pan ◽  
Xiao-Xue Ding ◽  
J. P. Draayer
Keyword(s):  
Mean Field ◽  
Order Parameters ◽  
Quantum Phase ◽  
Simple Description ◽  
Effective Order ◽  
Spherical Mean ◽  
Crossover Behavior ◽  
Pairing Model ◽  
The Mean

The shape phase crossover in the mean-field plus the geometric quadrupole–quadrupole and pairing model within two [Formula: see text]-orbits is analyzed, for which a simple description of [Formula: see text]Sn confined in the lowest [Formula: see text] and [Formula: see text] orbits above the [Formula: see text]Sn core is demonstrated to reveal the crossover behavior of the model. It is shown that [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text] in this case may serve as effective order parameters for even–even and odd-A systems, respectively, from which the shape phase crossover from the rotation-like phase to the superconducting-like phase can be observed with variation of the number of valence neutrons.

PHENOMENOLOGICAL THEORY OF HIGH Tc SUPERCONDUCTORS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 997-1000 ◽  
Author(s):  
M.P. Das ◽  
A.G. Saif
Keyword(s):  
Electrical Conductivity ◽  
Mean Field ◽  
Phenomenological Theory ◽  
Phenomenological Approach ◽  
Order Parameters ◽  
High Tc Superconductors ◽  
High Tc ◽  
Field Approach ◽  
Superconducting Ceramics ◽  
The Mean

We present a phenomenological approach in terms of two coexisting macroscopic order parameters correponding to the superconducting and the insulating states relevant to the high. temperature superconducting ceramics. On using the mean field approach we discuss the electrodynamical responses and from the fluctuations of the order parameters we obtain results for the electrical conductivity, which is shown to possess anomalies as in the granular materials.

scholarly journals Exact solution of spherical mean-field plus special orbit-dependent non-separable pairing model with multi non-degenerate j-orbits

2019 ◽  
Vol 795 ◽  
pp. 165-171 ◽  
Author(s):  
Feng Pan ◽  
Dan Zhou ◽  
Yingwen He ◽  
Siyu Yang ◽  
Yunfeng Zhang ◽  
...  
Keyword(s):  
Exact Solution ◽  
Mean Field ◽  
Spherical Mean ◽  
Pairing Model

scholarly journals An exact solution of spherical mean-field plus orbit-dependent non-separable pairing model with two non-degenerate j-orbits

2019 ◽  
Vol 984 ◽  
pp. 68-76 ◽  
Author(s):  
Feng Pan ◽  
Shuli Yuan ◽  
Yingwen He ◽  
Yunfeng Zhang ◽  
Siyu Yang ◽  
...  
Keyword(s):  
Exact Solution ◽  
Mean Field ◽  
Spherical Mean ◽  
Pairing Model

FLUCTUATION EFFECTS IN A CLASS OF SYSTEMS WITH TWO ORDER PARAMETERS

1993 ◽  
Vol 07 (27) ◽  
pp. 1725-1731 ◽  
Author(s):  
L. DE CESARE ◽  
I. RABUFFO ◽  
D.I. UZUNOV
Keyword(s):  
Phase Transition ◽  
Renormalization Group ◽  
Phase Transitions ◽  
Order Phase Transition ◽  
Mean Field ◽  
Ising Models ◽  
Order Parameters ◽  
The Mean ◽  
Fluctuation Effects ◽  
Second Order Phase Transition

The phase transitions described by coupled spin -1/2 Ising models are investigated with the help of the mean field and the renormalization group theories. Results for the type of possible phase transitions and their fluctuation properties are presented. A fluctuation-induced second-order phase transition is predicted.

Molecular Polarizabilities and Orientational Ordering of Two Mesogens

1991 ◽  
Vol 46 (10) ◽  
pp. 858-864 ◽  
Author(s):  
M. Mitra ◽  
S. Paul ◽  
R. Paul
Keyword(s):  
Field Theory ◽  
Liquid Crystalline ◽  
Mean Field Theory ◽  
Orientational Order ◽  
Mean Field ◽  
Continuum Theory ◽  
Order Parameters ◽  
Liquid Phases ◽  
Molecular Polarizabilities ◽  
The Mean

AbstractThe refractive indices (no, ne) and densities of two mesogens have been measured in their liquid crystalline and liquid phases. The molecular polarizabilities (xo, xe) were evaluated by Vuks' and Neugebauer's relations. The polarizabilities thus obtained are compared with those estimated from the bond polarizabilities, and the orientational order parameters, <P2>, are compared with the mean field theory of Maier and Saupe, the modified mean field theory of Humphries, James and Luckhurst. and the continuum theory suggested by T. E. Faber. We have also calculated the three order parameters (<P2), τ, σ) describing the smectic A phase following McMillan's model. Possible causes of the discrepancy are discussed.

ANALYTICAL EXPRESSIONS OF THE ORDER PARAMETERS NEAR THE TRANSITION TEMPERATURES IN THE SPIN-3/2 ISING SYSTEM WITH BILINEAR AND BIQUADRATIC INTERACTIONS

2006 ◽  
Vol 20 (04) ◽  
pp. 455-467 ◽  
Author(s):  
OSMAN CANKO ◽  
MUSTAFA KESKIN
Keyword(s):  
Phase Transitions ◽  
Mean Field ◽  
Field Approximation ◽  
Irreversible Thermodynamics ◽  
Order Parameters ◽  
Mean Field Approximation ◽  
Transition Temperatures ◽  
Ising System ◽  
The Mean ◽  
Analytical Expressions

Analytical expressions of the order parameters near the transition temperatures in the spin-3/2 Ising system with bilinear (J) and biquadratic (K) interactions are presented for various values of J/K. First, we obtain the free energy expression and the equations to determine order parameters by using the mean-field approximation. Then, the order parameters are expressed in the vicinity of the transition temperatures in which these expressions are very important to study the dynamics of the system by means of Onsager's theory of irreversible thermodynamics. Hence, we investigate the phase transitions occurring in the system and also obtain two tricritical points analytically. Finally, the specific heat and magnetic susceptibility are calculated and an argument about the critical exponents at the second-order phase transitions and tricritical points is given.

Multiband superconductivity with competing intra- and interband pair channels

2016 ◽  
Vol 30 (13) ◽  
pp. 1642017
Author(s):  
N. Kristoffel ◽  
P. Rubin
Keyword(s):  
Mean Field ◽  
Equation System ◽  
Order Parameters ◽  
Band Model ◽  
Multiband Superconductivity ◽  
Complicated Structure ◽  
General Behaviour ◽  
Interband Interaction ◽  
Extremal Points ◽  
The Mean

In multiband superconductivity interband interaction channels creating the pairs of intraband [Formula: see text] and interband [Formula: see text] compositions can appear. Simultaneous functioning of these channels is investigated here. A three-band model where two similar bands [Formula: see text] interact with the itinerant-band has been proposed. The mean field Hamiltonian incorporates three order parameters [Formula: see text]; [Formula: see text]; [Formula: see text] genetically associated with dispersive bands. Calculated quasiparticle energies and operator averages lead to a coupled nonlinear equation system for the order parameters. Illustrative calculations versus temperature have been made for overlapping bands. At fixed parameters, the basic system has two independent solutions. The free energy has a complicated structure of extremal points. The interaction of channels with intra- and interband points is seen. These channels compete in general. From the point where the gap, type parameters associated with one channel become zero, the other continues as the first channel was logged out. The general behaviour of order parameters distribution is very sensible to [Formula: see text]. Events of critical nature appear. Weakening of [Formula: see text] stimulates the formation of closed bubbles built up by the same type parameters from different parallel solutions.

scholarly journals An exact solution of spherical mean-field plus a special separable pairing model

2017 ◽  
Vol 957 ◽  
pp. 51-59 ◽  
Author(s):  
Lianrong Dai ◽  
Feng Pan ◽  
J.P. Draayer
Keyword(s):  
Exact Solution ◽  
Mean Field ◽  
Spherical Mean ◽  
Pairing Model

scholarly journals Level statistics of the spherical mean-field plus pairing model

2013 ◽  
Vol 63 ◽  
pp. 01011
Author(s):  
Feng Pan ◽  
Xin Guan ◽  
Kristina D. Launey ◽  
Jianzhong Gu ◽  
Jerry P. Draayer
Keyword(s):  
Mean Field ◽  
Spherical Mean ◽  
Level Statistics ◽  
Pairing Model
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