Exotic Properties of Superfluid Helium 3

Volovik, G. E.

doi:10.1142/1439

Cited by 337 publications

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“…In s-wave superfluids quasi-particle excitations are always gapped and the evolution from the BCS to the BEC regime is smooth, so that no quantum phase transition occurs. This gapless to gapped quantum phase transitions were first considered in the context of He 3 by Volovik 47 , and later in the context of high-T c superconductivity 48,49 and atomic Fermi gases 11,13 .…”

Section: B Quasi-particle Excitation Spectrummentioning

confidence: 95%

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Iskin¹,

Melo²

2005

Phys. Rev. B

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We consider p-wave pairing of single hyperfine state and s-wave pairing of two hyperfine states ultracold atomic gases trapped in quasi-two-dimensional optical lattices. First, we analyse superfluid properties of p-wave and s-wave symmetries in the strictly weak coupling BCS regime where we discuss the order parameter, chemical potential, critical temperature, atomic compressibility and superfluid density as a function of filling factor for tetragonal and orthorhombic optical lattices. Second, we analyse superfluid properties of p-wave and s-wave superfluids in the evolution from BCS to BEC regime at low temperatures (T ≈ 0), where we discuss the changes in the quasi-particle excitation spectrum, chemical potential, atomic compressibility, Cooper pair size and momentum distribution as a function of filling factor and interaction strength for tetragonal and orthorhombic optical lattices.

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Section: B Quasi-particle Excitation Spectrummentioning

confidence: 95%

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Iskin¹,

Melo²

2005

Phys. Rev. B

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“…In what follows, we discuss the role of momentum space topology 28,38,45 in the non-analytic behavior of the thermodynamic potential, when µ ℓ =0 = 0. To investigate the role of topology, we make an immediate connection to the Lifshitz transition 46 in the context of ordinary metals at T = 0 and high pressure.…”

Section: E Topological Quantum Phase Transitionsmentioning

confidence: 99%

Nonzero orbital angular momentum superfluidity in ultracold Fermi gases

Iskin¹,

Melo

2006

Phys. Rev. A

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We analyze the evolution of superfluidity for nonzero orbital angular momentum channels from the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein condensation (BEC) limit in three dimensions. First, we analyze the low energy scattering properties of finite range interactions for all possible angular momentum channels. Second, we discuss ground state (T = 0) superfluid properties including the order parameter, chemical potential, quasiparticle excitation spectrum, momentum distribution, atomic compressibility, ground state energy and low energy collective excitations. We show that a quantum phase transition occurs for nonzero angular momentum pairing, unlike the s-wave case where the BCS to BEC evolution is just a crossover. Third, we present a gaussian fluctuation theory near the critical temperature (T = Tc), and we analyze the number of bound, scattering and unbound fermions as well as the chemical potential. Finally, we derive the time-dependent Ginzburg-Landau functional near Tc, and compare the Ginzburg-Landau coherence length with the zero temperature average Cooper pair size.

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“…For 2D electron gas (2DEG), the total number of quantum states is given by N = g A (2π) 2 πk 2 F , where g is the degeneracy factor (spin) and A is the area. Then the density is n = N/A = gk 2 F 4π = gm 2π 2 µ. Analogously, for 3D electron gas (3DEG), N = g V (2π) 3 4π 3 k F 3 , where V is the volume, and n = N/V = gk 3 F 6π 2 = gm 6π 2 3 ( √ 2mµ) 3 . Substituting expressions for electron density into Eqs.…”

Section: Appendix B: Derivation Of the Interacting Weyl Hamiltonianmentioning

confidence: 96%

“…In Eq. (45), the trace over velocities and spectral functions gives an expression proportional to 3 . The integral over momentum k can then be transformed into an integral over energy ε after performing angular integration.…”

Section: Appendix B: Derivation Of the Interacting Weyl Hamiltonianmentioning

confidence: 99%

Excitonic instability in optically pumped three-dimensional Dirac materials

Pertsova

Balatsky

2018

Phys. Rev. B

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Recently it was suggested that transient excitonic instability can be realized in optically-pumped two-dimensional (2D) Dirac materials (DMs), such as graphene and topological insulator surface states. Here we discuss the possibility of achieving a transient excitonic condensate in opticallypumped three-dimensional (3D) DMs, such as Dirac and Weyl semimetals, described by nonequilibrium chemical potentials for photoexcited electrons and holes. Similar to the equilibrium case with long-range interactions, we find that for pumped 3D DMs with screened Coulomb potential two possible excitonic phases exist, an excitonic insulator phase and the charge density wave phase originating from intranodal and internodal interactions, respectively. In the pumped case, the critical coupling for excitonic instability vanishes; therefore, the two phases coexist for arbitrarily weak coupling strengths. The excitonic gap in the charge density wave phase is always the largest one. The competition between screening effects and the increase of the density of states with optical pumping results in a reach phase diagram for the transient excitonic condensate. Based on the static theory of screening, we find that under certain conditions for the value of the dimensionless coupling constant screening in 3D DMs can be weaker than in 2D DMs. Furthermore, we identify the signatures of the transient excitonic condensate that could be probed by scanning tunneling spectroscopy, photoemission and optical conductivity measurements. Finally, we provide estimates of critical temperatures and excitonic gaps for existing and hypothetical 3D DMs.

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Exotic Properties of Superfluid Helium 3

Cited by 337 publications

References 0 publications

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Nonzero orbital angular momentum superfluidity in ultracold Fermi gases

Excitonic instability in optically pumped three-dimensional Dirac materials

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