Phase diagram of a uniform two-dimensional Fermi gas with spin-orbit coupling

Yang, Xiurong; Wan, Shaolong

doi:10.1103/physreva.85.023633

Cited by 45 publications

(79 citation statements)

References 39 publications

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“…These laser beams couple two internal hyperfine states of the atom by a stimulated two-photon Raman transition [1][2][3][4]. Triggered by these remarkable experiments, in the last few years a large number of theoretical papers have analyzed the spin-orbit effects with Rashba [5] and Dresselhaus [6] terms in Bose-Einstein condensates [7][8][9][10][11][12][13] and also in the BCS-BEC crossover of superfluid fermions [14][15][16][17][18][19][20][21][22]. Very recently, the Rashba spin-orbit coupling in a two-dimensional (2D) repulsive Fermi gas has been investigated in [23,24], where the density of states is quite simple and analytical results can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Itinerant ferromagnetism of two-dimensional repulsive fermions with Rabi coupling

Penna

Salasnich

2017

New J. Phys.

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We study a two-dimensional fermionic cloud of repulsive alkali-metal atoms characterized by two hyperfine states which are Rabi coupled. Within a variational Hartree-Fock scheme, we calculate analytically the ground-state energy of the system. Then we determine the conditions under which there is a quantum phase transition with spontaneous symmetry breaking from a spin-balanced configuration to a spin-polarized one, an effect known as itinerant ferromagnetism. Interestingly, we find that the transition appears when the interaction energy per particle exceedes both the kinetic energy per particle and the Rabi coupling energy. The itinerant ferromagnetism of the polarized phase is analyzed, obtaining the population imbalance as a function of interaction strength, Rabi coupling, and number density. Finally, the inclusion of a external harmonic confinement is investigated by adopting the local density approximation. We predict that a single atomic cloud can display population imbalance near the center of the trap and a fully balanced configuration at the periphery.

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Section: Introductionmentioning

confidence: 99%

Itinerant ferromagnetism of two-dimensional repulsive fermions with Rabi coupling

Penna

Salasnich

2017

New J. Phys.

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“…In such systems the strength of the coupling can be optically tuned; this is indeed also a useful tool for ultracold fermions [28,29]. These achievements have stimulated theoretical efforts in understanding the spinorbit effects with Rashba [30] and Dresselhaus [31] terms in the BCS-BEC crossover [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. The evolution from BCS to BEC superfluidity was intensively studied in the presence of spin-orbit coupling for a three-dimensional (3D) uniform Fermi gas [33][34][35][36][37][38][39][40]42,43,45] and in the 2D case [39,41,[44][45][46]49].…”

Section: Introductionmentioning

confidence: 99%

Tuning Rashba and Dresselhaus spin-orbit couplings: Effects on singlet and triplet condensation with Fermi atoms

2012

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We investigate the pair condensation of a two-spin component Fermi gas in the presence of both Rashba and Dresselhaus spin-orbit couplings. We calculate the condensate fraction in the BCS-BEC (Bardeen-Cooper-Schrieffer–Bose-Einstein condensate) crossover in both two and three dimensions by taking into account singlet and triplet pairings. These quantities are studied by varying the spin-orbit interaction from the case with the only-Rashba to the equal-Rashba-Dresselhaus one. We find that by mixing the two couplings, the singlet pairing decreases while the triplet pairing is suppressed in the BCS regime and increased in the BEC regime, both in two and three dimensions. At fixed spin-orbital strength, the greatest total condensate fraction is obtained when only one coupling (only Rashba or only Dresselhaus) is present

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“…(10), and the corresponding eigenstate can be extracted from Eqs. (11)- (14). As typical examples, we focus on the s-wave wide Feshbach resonances around B 0 = 202 G for 40 K and B 0 = 834 G for 6 Li.…”

Section: Two-body Bound State In Quasi-2d Confinementmentioning

confidence: 99%

“…Recent experimental realizations of spin-orbit coupling (SOC) in ultracold atoms [1][2][3] stimulate a new wave of exploration for exotic phases in polarized Fermi gases [4][5][6][7][8][9][10][11][12][13][14][15][16]. The competition between polarization, pairing superfluidity, and SOC gives rise to rich phase structures.…”

Section: Introductionmentioning

confidence: 99%

Significance of dressed molecules in a quasi-two-dimensional Fermi gas with spin-orbit coupling

Zhang

Tang

et al. 2013

Phys. Rev. A

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We investigate the properties of a spin-orbit coupled quasi-two-dimensional Fermi gas with tunable s-wave interaction between the two spin species. By analyzing the two-body bound state, we find that the population of the excited states in the tightly confined axial direction can be significant when the two-body binding energy becomes comparable to or exceeds the axial confinement. Since the Rashba spin-orbit coupling that we study here tends to enhance the two-body binding energy, this effect can become prominent at unitarity or even on the BCS side of the Feshbach resonance. To study the impact of these excited modes along the third dimension, we adopt an effective two-dimensional Hamiltonian in the form of a two-channel model, where the dressed molecules in the closed channel consist of the conventional Feshbach molecules as well as the excited states occupation in the axial direction. With properly renormalized interactions between atoms and dressed molecules, we find that both the density distribution and the phase structure in the trap can be significantly modified near a wide Feshbach resonance. In particular, the stability region of the topological superfluid phase is increased. Our findings provide a proper description for a quasi-two-dimensional Fermi gas under spin-orbit coupling, and are helpful for the experimental search for the topological superfluid phase in ultracold Fermi gases.

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Phase diagram of a uniform two-dimensional Fermi gas with spin-orbit coupling

Cited by 45 publications

References 39 publications

Itinerant ferromagnetism of two-dimensional repulsive fermions with Rabi coupling

Itinerant ferromagnetism of two-dimensional repulsive fermions with Rabi coupling

Tuning Rashba and Dresselhaus spin-orbit couplings: Effects on singlet and triplet condensation with Fermi atoms

Significance of dressed molecules in a quasi-two-dimensional Fermi gas with spin-orbit coupling

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