Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:0809.1420 · Acta Physica Polonica A

Some Properties of the Spin-Polarized Attractive Hubbard Model

Agnieszka Kujawa, R. Micnas

Published Jan 1, 2009• 5 citations
arXivHTMLPDF

Abstract

The influence of a Zeeman magnetic field on the superconducting characteristics of the attractive Hubbard model was investigated.The ground state and temperature phase diagrams were obtained for a fixed number of particles.Two critical magnetic fields were found for the first order phase transition from the superconducting to the normal state for n = 1.For some range of parameters a reentrant transition was found and gapless superconductivity was obtained.The significance of the Hartree term was also analyzed.

DOI
10.12693/aphyspola.115.138

Related papers

On the Phase Diagram of Spin-Polarized Attractive Hubbard Model: Weak Coupling Limit

Agnieszka Kujawa, R. Micnas

The superfluid properties of the attractive Hubbard model in a Zeeman magnetic field, and in the weak coupling regime were investigated.The temperature and magnetic field dependences of the order parameter were analyzed.Furthermore, the temperature vs. magnetic field and temperature vs. spin polarization phase diagrams for the 2D and 3D lattices were obtained.For some parameters a reentrant transition was found.

arXiv:0808.1578•Acta Physica Polonica A•Jul 1, 2008•8 citations

On the BCS-BEC Crossover in the Spin-Polarized Attractive Hubbard Model at T=0

Agnieszka Cichy

The influence of the Zeeman magnetic field (h) on the ground state evolution of superfluid properties from the weak coupling (BCS-like) to the strong coupling limit of tightly bound local pairs with increasing attraction has been studied.The analysis was carried out within the spin-polarized attractive Hubbard model, for a fixed number of particles and a d = 3 simple cubic lattice.The broken symmetry Hartree approximation was used.For strong attraction and in the dilute limit, the homogeneous magnetized superconducting phase (SC M ) was found in the h-|U | and P -|U | diagrams.

arXiv:1309.6667•Acta Physica Polonica A•Aug 1, 2010•5 citations

The phase diagram and inhomogenous superconductivity in the one-dimensional attractive Hubbard model

Kocharian AN; Yang C; Chiang YL

[[abstract]]The thermodynamic phase diagram of the attractive Hubbard model in the presence of magnetic field is calculated in wide range of temperature, electron concentration and coupling strength within the generalized self-consistent field (GSCF) approach, including the spin density correlations. The theory provides a smooth transition driven by applied magnetic field IL and temperature T from the homogeneous superconducting state into a spatially inhomogeneous state with the order parameter Delta ((-))(Q) not equal 0.

•Jan 1, 2000•0 citations

Stability of superfluid phases in the 2D spin-polarized attractive Hubbard model

A. Kujawa-Cichy, R. Micnas

We study the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (LPs) with increasing attraction, in the presence of the Zeeman magnetic field ( h ) for d =2, within the spin-polarized attractive Hubbard model. The broken symmetry Hartree approximation as well as the strong coupling expansion are used. We also apply the Kosterlitz-Thouless (KT) scenario to determine the phase coherence temperatures. For spin-independent hopping integrals ( t ↑ = t ↓ ), we find no stable homogeneous polarized superfluid (SC M ) state in the ground state for the strong attraction and obtain that for a two-component Fermi system on a 2D lattice with population imbalance, phase separation (PS) is favoured for a fixed particle concentration, even on the LP (BEC) side. We also examine the influence of spin-dependent hopping integrals (mass imbalance) on the stability of the SC M phase. We find a topological quantum phase transition (Lifshitz type) from the unpolarized superfluid phase (SC 0 ) to SC M and tricritical points in the h -| U | and t ↑ / t ↓ -| U | ground-state phase diagrams. We also construct the finite temperature phase diagrams for both t ↑ = t ↓ and t ↑ ≠ t ↓ and analyze the possibility of occurrence of a spin-polarized KT superfluid.

arXiv:1309.6668•Europhysics Letters (EPL)•Jul 15, 2011•13 citations

The influence of magnetic field on the superconducting properties and the BCS-BEC crossover in systems with local fermion pairing

Agnieszka Cichy

The aim of this Ph.D. thesis was to investigate superconducting properties in the presence of Zeeman magnetic field in systems with local fermion pairing on the lattice. The study also concerned the evolution from the weak coupling (BCS-like) limit to the strong coupling limit of tightly bound local pairs (BEC) with increasing attraction, both in the ground state and at finite temperatures, within the spin-polarized extended Hubbard model. The analysis was also extended to the case of spin dependent hopping integrals (mass imbalance), with special attention paid to the BCS-BEC crossover physics in the ground state. The methods used included: the mean field approximation (BCS-Stoner type) and the estimation of the phase coherence temperature within the Kosterlitz-Thouless (KT) scenario in two dimensions. The BCS-BEC crossover was also analyzed in three dimensions, at finite temperatures, within the spin polarized Attractive Hubbard Model (AHM), going beyond the mean field approximation. In this case, the critical temperatures of the superconducting transition were determined within the self-consistent T-matrix method. The strong coupling expansion was applied to map the spin polarized AHM onto the model of hard-core bosons on the lattice.

arXiv:1309.6680•Sep 25, 2013•2 citations

Phase Transitions in Quasi-One-Dimensional System with Unconventional Superconductivity

Andrzej Ptok, Agnieszka Cichy, Karen Rodríguez +1 more

The paper is devoted to a study of superconducting properties of population-imbalanced fermionic mixtures in quasi -one-dimensional optical lattices. The system can be effectively described by the attractive Hubbard model with the Zeeman magnetic field term. We investigated the ground-state phase diagram of the model as a function of the chemical potential and the magnetic field. The ground state of the system exhibits the conventional BCS-type superconductivity as well as the unconventional so-called Fulde-Ferrell-Larkin-Ovchinnikov state, in which the total momentum of Cooper pairs is non-zero. We determine the orders of transitions as well as the behavior of order parameters with a change of the model parameters.

arXiv:1710.01668•Journal of Superconductivity and Novel Magnetism•Oct 3, 2017•8 citations
The influence of a Zeeman magnetic field on the superconducting characteristics of the attractive Hubbard model was investigated.The ground state and temperature phase diagrams were obtained for a fixed number of particles.Two critical magnetic fields were found for the first order phase transition from the superconducting to the normal state for n = 1.For some range of parameters a reentrant transition was found and gapless superconductivity was obtained.The significance of the Hartree term was also analyzed.
The influence of the Zeeman magnetic field (h) on the ground state evolution of superfluid properties from the weak coupling (BCS-like) to the strong coupling limit of tightly bound local pairs with increasing attraction has been studied.The analysis was carried out within the spin-polarized attractive Hubbard model, for a fixed number of particles and a d = 3 simple cubic lattice.The broken symmetry Hartree approximation was used.For strong attraction and in the dilute limit, the homogeneous magnetized superconducting phase (SC M ) was found in the h-|U | and P -|U | diagrams.
[[abstract]]The thermodynamic phase diagram of the attractive Hubbard model in the presence of magnetic field is calculated in wide range of temperature, electron concentration and coupling strength within the generalized self-consistent field (GSCF) approach, including the spin density correlations. The theory provides a smooth transition driven by applied magnetic field IL and temperature T from the homogeneous superconducting state into a spatially inhomogeneous state with the order parameter Delta ((-))(Q) not equal 0.
We study the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (LPs) with increasing attraction, in the presence of the Zeeman magnetic field ( h ) for d =2, within the spin-polarized attractive Hubbard model. The broken symmetry Hartree approximation as well as the strong coupling expansion are used. We also apply the Kosterlitz-Thouless (KT) scenario to determine the phase coherence temperatures. For spin-independent hopping integrals ( t ↑ = t ↓ ), we find no stable homogeneous polarized superfluid (SC M ) state in the ground state for the strong attraction and obtain that for a two-component Fermi system on a 2D lattice with population imbalance, phase separation (PS) is favoured for a fixed particle concentration, even on the LP (BEC) side. We also examine the influence of spin-dependent hopping integrals (mass imbalance) on the stability of the SC M phase. We find a topological quantum phase transition (Lifshitz type) from the unpolarized superfluid phase (SC 0 ) to SC M and tricritical points in the h -| U | and t ↑ / t ↓ -| U | ground-state phase diagrams. We also construct the finite temperature phase diagrams for both t ↑ = t ↓ and t ↑ ≠ t ↓ and analyze the possibility of occurrence of a spin-polarized KT superfluid.
The aim of this Ph.D. thesis was to investigate superconducting properties in the presence of Zeeman magnetic field in systems with local fermion pairing on the lattice. The study also concerned the evolution from the weak coupling (BCS-like) limit to the strong coupling limit of tightly bound local pairs (BEC) with increasing attraction, both in the ground state and at finite temperatures, within the spin-polarized extended Hubbard model. The analysis was also extended to the case of spin dependent hopping integrals (mass imbalance), with special attention paid to the BCS-BEC crossover physics in the ground state. The methods used included: the mean field approximation (BCS-Stoner type) and the estimation of the phase coherence temperature within the Kosterlitz-Thouless (KT) scenario in two dimensions. The BCS-BEC crossover was also analyzed in three dimensions, at finite temperatures, within the spin polarized Attractive Hubbard Model (AHM), going beyond the mean field approximation. In this case, the critical temperatures of the superconducting transition were determined within the self-consistent T-matrix method. The strong coupling expansion was applied to map the spin polarized AHM onto the model of hard-core bosons on the lattice.
The paper is devoted to a study of superconducting properties of population-imbalanced fermionic mixtures in quasi -one-dimensional optical lattices. The system can be effectively described by the attractive Hubbard model with the Zeeman magnetic field term. We investigated the ground-state phase diagram of the model as a function of the chemical potential and the magnetic field. The ground state of the system exhibits the conventional BCS-type superconductivity as well as the unconventional so-called Fulde-Ferrell-Larkin-Ovchinnikov state, in which the total momentum of Cooper pairs is non-zero. We determine the orders of transitions as well as the behavior of order parameters with a change of the model parameters.