BCS-BEC Crossover and Topological Phase Transition in 3D Spin-Orbit Coupled Degenerate Fermi Gases

Gong, Ming; Tewari, Sumanta; Zhang, Chuanwei

doi:10.1103/physrevlett.107.195303

Cited by 262 publications

(301 citation statements)

References 31 publications

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“…Usually the robust topological protection is associated with a non-zero spectral gap in the bulk of the system, and the presence of protected zero energy surface states is regarded as the hallmark of a non-trivial topological phase of matter. However, recently it has been proposed that systems in three spatial dimensions, in the presence of broken time-reversal (TR) and/or spaceinversion (SI) symmetry, can also be topologically protected even without a bulk energy gap [10][11][12][13][14][15][16][17][18][19][20][21] . These are Weyl semimetals (WSM) -the nomenclature based on the Dirac/Weyl equation which is used to describe their low energy excitations 22 .…”

Section: Introductionmentioning

confidence: 99%

Nernst and magnetothermal conductivity in a lattice model of Weyl fermions

Sharma¹,

Goswami²,

Tewari³

2016

Phys. Rev. B

Self Cite

183

191

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Weyl semimetals (WSM) are topologically protected three dimensional materials whose low energy excitations are linearly dispersing massless Dirac fermions, possessing a non-trivial Berry curvature. Using semiclassical Boltzmann dynamics in the relaxation time approximation for a lattice model of time reversal (TR) symmetry broken WSM, we compute both magnetic field dependent and anomalous contributions to the Nernst coefficient. In addition to the magnetic field dependent Nernst response, which is present in both Dirac and Weyl semimetals, we show that, contrary to previous reports, the TR-broken WSM also has an anomalous Nernst response due to a non-vanishing Berry curvature. We also compute the thermal conductivities of a WSM in the Nernst (∇T ⊥ B) and the longitudinal (∇T B) set-up and confirm from our lattice model that in the parallel set-up, the Wiedemann-Franz law is violated between the longitudinal thermal and electrical conductivities due to chiral anomaly.

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Section: Introductionmentioning

confidence: 99%

Nernst and magnetothermal conductivity in a lattice model of Weyl fermions

Sharma¹,

Goswami²,

Tewari³

2016

Phys. Rev. B

Self Cite

183

191

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“…Recently synthetic gauge fields [6] and spin-orbit (SO) coupling [7][8][9][10][11] were realized in experiments, opening up a completely new avenue of research in superfluid Fermi gases. The interplay of Zeeman fields and SO coupling leads to many novel phenomena at both zero [12][13][14][15][16][17] and finite temperatures [18,19], from mixed singlet-triplet pairing to topological phase transition [12,[20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic properties of Rashba spin-orbit-coupled Fermi gas

Zheng

Zou

et al. 2014

Phys. Rev. A

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We investigate the thermodynamic properties of a superfluid Fermi gas subject to Rashba spinorbit coupling and effective Zeeman field. We adopt a T-matrix scheme that takes beyond-meanfield effects, which are important for strongly interacting systems, into account. We focus on the calculation of two important quantities: the superfluid transition temperature and the isothermal compressibility. Our calculation shows very distinct influences of the out-of-plane and the in-plane Zeeman fields on the Fermi gas. We also confirm that the in-plane Zeeman field induces a FuldeFerrell superfluid below the critical temperature and an exotic finite-momentum pseudo-gap phase above the critical temperature.

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“…A variety of intriguing phenomena such as non-equilibrium dynamics [9,10], the spin-orbit coupling assisted formation of molecules [7], and the engineering of band structures [11] have been investigated. At the mean-field level, spin-orbit coupled gases exhibit rich phase diagrams [4,[12][13][14][15][16][17][18]. Effects beyond mean-field theory [19][20][21][22], associated with the renormalization of interactions, are enhanced by the spin-orbit coupling, especially in the pure Rashba case, and can qualitatively change the mean-field results.…”

Section: Introductionmentioning

confidence: 99%

“…The c (2) nρ,m l ,ms -coefficients can be read off Eq. (17). Figures 2(c) and 2(d) illustrate the non-zero matrix elements that contribute to the energy shift of the ground state at fourth-order perturbation theory.…”

Section: Weak Atom-atom Interaction and Weak Spin-orbit Couplingmentioning

confidence: 99%

Harmonically trapped two-atom systems: Interplay of short-ranges-wave interaction and spin-orbit coupling

Yin

Gopalakrishnan²,

Blume

2014

Phys. Rev. A

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The coupling between the spin degrees of freedom and the orbital angular momentum has a profound effect on the properties of nuclei, atoms and condensed matter systems. Recently, synthetic gauge fields have been realized experimentally in neutral cold atom systems, giving rise to a spin-orbit coupling term with "strength" kso. This paper investigates the interplay between the single-particle spin-orbit coupling term of Rashba type and the short-range two-body s-wave interaction for cold atoms under external confinement. Specifically, we consider two different harmonically trapped two-atom systems. The first system consists of an atom with spin-orbit coupling that interacts with a structureless particle through a short-range two-body potential. The second system consists of two atoms that both feel the spin-orbit coupling term and that interact through a short-range two-body potential. Treating the spin-orbit term perturbatively, we determine the correction to the ground state energy for various generic parameter combinations. Selected excited states are also treated. An important aspect of our study is that the perturbative treatment is not limited to small s-wave scattering lengths but provides insights into the system behavior over a wide range of scattering lengths, including the strongly-interacting unitary regime. We find that the interplay between the spin-orbit coupling term and the s-wave interaction generically enters, depending on the exact parameter combinations of the s-wave scattering lengths, at order k 2 so or k 4 so for the ground state and leads to a shift of the energy of either sign. While the absence of a term proportional to kso follows straightforwardly from the functional form of the spin-orbit coupling term, the absence of a term proportional to k 2 so for certain parameter combinations is unexpected. The well-known fact that the spin-orbit coupling term couples the relative and center of mass degrees of freedom has interesting consequences for the trapped two-particle systems. For example, we find that the spin-orbit coupling term turns, for certain parameter combinations, sharp crossings into avoided crossings with an energy splitting proportional to kso. Our perturbative results are confirmed by numerical calculations that expand the eigenfunctions of the two-particle Hamiltonian in terms of basis functions that contain explicitly correlated Gaussians.

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BCS-BEC Crossover and Topological Phase Transition in 3D Spin-Orbit Coupled Degenerate Fermi Gases

Cited by 262 publications

References 31 publications

Nernst and magnetothermal conductivity in a lattice model of Weyl fermions

Nernst and magnetothermal conductivity in a lattice model of Weyl fermions

Thermodynamic properties of Rashba spin-orbit-coupled Fermi gas

Harmonically trapped two-atom systems: Interplay of short-ranges-wave interaction and spin-orbit coupling

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