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Unconventional pairings of spin-orbit coupled attractive degenerate Fermi gas in a one-dimensional optical lattice.

Liang J, Zhou X, Chui PH, Zhang K, Gu SJ, Gong M, Chen G, Jia S - Sci Rep (2015)

Bottom Line: We figure out the whole phase diagrams as functions of filling factor, SOC strength, and Zeeman field.Our results are qualitatively different from recent mean-field predictions.Finally, we address that our predictions could be observed in a weaker trapped potential.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.

ABSTRACT
Understanding novel pairings in attractive degenerate Fermi gases is crucial for exploring rich superfluid physics. In this report, we reveal unconventional pairings induced by spin-orbit coupling (SOC) in a one-dimensional optical lattice, using a state-of-the-art density-matrix renormalization group method. When both bands are partially occupied, we find a strong competition between the interband Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) and intraband Bardeen-Cooper-Schrieffer (BCS) pairings. In particular, for the weak and moderate SOC strengths, these two pairings can coexist, giving rise to a new phase called the FFLO-BCS phase, which exhibits a unique three-peak structure in pairing momentum distribution. For the strong SOC strength, the intraband BCS pairing always dominates in the whole parameter regime, including the half filling. We figure out the whole phase diagrams as functions of filling factor, SOC strength, and Zeeman field. Our results are qualitatively different from recent mean-field predictions. Finally, we address that our predictions could be observed in a weaker trapped potential.

No MeSH data available.


Related in: MedlinePlus

The critical SOC strengths λc as functions of the lattice length.In this figure, n = 1 and h/t = 1.5.
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f10: The critical SOC strengths λc as functions of the lattice length.In this figure, n = 1 and h/t = 1.5.

Mentions: It should be pointed out that the boundary condition may influence the spin polarizations at the two ends; however, it does not affect our main predictions about spin polarizations in both real and momentum spaces, as demonstrated in Figs. 4 and 5 with L = 60 and L = 100. We also do not observe phase separation in the open boundary condition. So we can exclude the possibility of three peaks in the FFLO-BCS phase from the phase-separation effect. In Fig. 10, we plot the critical SOC strengths λc, which govern the phase boundaries, as functions of the lattice length, when the Zeeman field h/t = 1.5 (the dash line of Fig. 12). In terms of this finite-size-scaling analysis, we find that when increasing the lattice length, our predicted FFLO-BCS phase, with a unique three-peak structure, still exists, although the center-of-mass momentum Q and the phase boundaries change slightly.


Unconventional pairings of spin-orbit coupled attractive degenerate Fermi gas in a one-dimensional optical lattice.

Liang J, Zhou X, Chui PH, Zhang K, Gu SJ, Gong M, Chen G, Jia S - Sci Rep (2015)

The critical SOC strengths λc as functions of the lattice length.In this figure, n = 1 and h/t = 1.5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595649&req=5

f10: The critical SOC strengths λc as functions of the lattice length.In this figure, n = 1 and h/t = 1.5.
Mentions: It should be pointed out that the boundary condition may influence the spin polarizations at the two ends; however, it does not affect our main predictions about spin polarizations in both real and momentum spaces, as demonstrated in Figs. 4 and 5 with L = 60 and L = 100. We also do not observe phase separation in the open boundary condition. So we can exclude the possibility of three peaks in the FFLO-BCS phase from the phase-separation effect. In Fig. 10, we plot the critical SOC strengths λc, which govern the phase boundaries, as functions of the lattice length, when the Zeeman field h/t = 1.5 (the dash line of Fig. 12). In terms of this finite-size-scaling analysis, we find that when increasing the lattice length, our predicted FFLO-BCS phase, with a unique three-peak structure, still exists, although the center-of-mass momentum Q and the phase boundaries change slightly.

Bottom Line: We figure out the whole phase diagrams as functions of filling factor, SOC strength, and Zeeman field.Our results are qualitatively different from recent mean-field predictions.Finally, we address that our predictions could be observed in a weaker trapped potential.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser spectroscopy, Shanxi University, Taiyuan 030006, P. R. China.

ABSTRACT
Understanding novel pairings in attractive degenerate Fermi gases is crucial for exploring rich superfluid physics. In this report, we reveal unconventional pairings induced by spin-orbit coupling (SOC) in a one-dimensional optical lattice, using a state-of-the-art density-matrix renormalization group method. When both bands are partially occupied, we find a strong competition between the interband Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) and intraband Bardeen-Cooper-Schrieffer (BCS) pairings. In particular, for the weak and moderate SOC strengths, these two pairings can coexist, giving rise to a new phase called the FFLO-BCS phase, which exhibits a unique three-peak structure in pairing momentum distribution. For the strong SOC strength, the intraband BCS pairing always dominates in the whole parameter regime, including the half filling. We figure out the whole phase diagrams as functions of filling factor, SOC strength, and Zeeman field. Our results are qualitatively different from recent mean-field predictions. Finally, we address that our predictions could be observed in a weaker trapped potential.

No MeSH data available.


Related in: MedlinePlus