scholarly journals Antiferromagnetism, charge density wave, andd-wave superconductivity in the extendedt-J-Umodel: role of intersite Coulomb interaction and a critical overview of renormalized mean field theory

2017 ◽  
Vol 29 (36) ◽  
pp. 365602 ◽  
Author(s):  
M Abram ◽  
M Zegrodnik ◽  
J Spałek
Keyword(s):  
Field Theory ◽  
Charge Density ◽  
Coulomb Interaction ◽  
Charge Density Wave ◽  
Mean Field Theory ◽  
Density Wave ◽  
Mean Field ◽  
Critical Overview ◽  
Intersite Coulomb Interaction

Ferromagnetism, Dimerization, Charge and Spin Density Waves in Quasi-One-Dimensional Organic Polymers: Self-Consistent Mean Field Theory

1998 ◽  
Vol 12 (20) ◽  
pp. 2031-2044 ◽  
Author(s):  
Shi-Dong Liang ◽  
Qianghua Wang ◽  
Z. D. Wang ◽  
Shun-Qing Shen
Keyword(s):  
Field Theory ◽  
Charge Density ◽  
Spin Density ◽  
Charge Density Wave ◽  
Mean Field Theory ◽  
Density Wave ◽  
Mean Field ◽  
One Dimensional ◽  
Ferromagnetic Order ◽  
Self Consistent

We address the low temperature properties of quasi-one-dimensional organic polymers, which may be described by a modified Anderson lattice-Su–Schrieffer–Heeger Hamiltonian. The condition and nature of various orders, such as, the ferromagnetic order, the dimerization order, the charge density wave order and the spin density wave order, are analyzed by a self-consistent mean field theory. Analytical results are obtained for a specific case. The topological structure of the chain leads to a flatband structure of the energy band, which gives rise to a ferromagnetic order in the case of half filling at low temperatures. The on-site Coulomb repulsion enhances the ferromagnetic order, while the nearest-neighbor interaction (V) suppresses both the ferromagnetic order and the dimerization, and leads to the charge density wave. The π–d hybridization (td) suppresses the dimerization, and does not affect the magnetization. The ferromagnetic order and dimerization order coexist for weak td.

scholarly journals Unitarity bound violation in holography and the instability toward the charge density wave

2020 ◽  
Vol 35 (22) ◽  
pp. 2050128
Author(s):  
Geunho Song ◽  
Yunseok Seo ◽  
Sang-Jin Sin
Keyword(s):  
Field Theory ◽  
Conformal Field Theory ◽  
Fermi Surface ◽  
Charge Density ◽  
Spectral Function ◽  
Charge Density Wave ◽  
Density Wave ◽  
Surface Phenomena ◽  
Unitarity Bound ◽  
Conformal Field

We study the spectral function of holographic fermions with Pauli term. We find the [Formula: see text]-dependent instability signaled by the tachyonic spectrum ([Formula: see text]-gap) from the [Formula: see text] regime where unitarity is violated. We suggest that this is the instability toward the charge density wave (CDW) based on the similarity of the unitarity violation in conformal field theory (CFT) and the nesting Fermi surface phenomena in weakly interaction system: both of them give divergent enhancement of degree of freedom.

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.

Role of molecular bend angle and biaxiality in the stabilization of the twist-bend nematic phase

Soft Matter ◽  
2020 ◽  
Vol 16 (18) ◽  
pp. 4350-4357 ◽  
Author(s):  
Wojciech Tomczyk ◽  
Lech Longa
Keyword(s):  
Field Theory ◽  
Nematic Phase ◽  
Mean Field Theory ◽  
Mean Field ◽  
Structural Features ◽  
Bend Angle ◽  
Nematic Phases

Within mean-field theory for V-shaped molecules, we have investigated how the alteration of a molecule's structural features influence the stabilization of modulated and non-modulated nematic phases.

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