Chiral universality class of normal-superconducting and exciton condensation transitions on surface of topological insulator

Li, Dingping; Rosenstein, Baruch; Shapiro, B. I.; Shapiro, I.

doi:10.1007/s11467-015-0465-1

Cited by 4 publications

(2 citation statements)

References 98 publications

(181 reference statements)

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“…We derive the Gorkov's equations within the functional integral approach [64,65] starting from the effective electron action for grassmanian fields ψ * σ k,n and ψ σ k,n . To simplify the presentation it is useful to lump the quasi -momentum and the Matsubara frequency into a single subscript, {n, k 1 , k 2 } → α,and the spin and sublattice into the four component spinor {σ, I} → a.…”

Section: Appendix C Derivation Of the Gap Equation In Underdoped Systemmentioning

confidence: 99%

Apical oxygen vibrations dominant role in d-wave cuprate superconductivity and its interplay with spin fluctuations

Rosenstein¹,

Shapiro²

2020

Preprint

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Microscopic theory of a high Tc cuprate Bi2Sr2CaCu2O8+x based on main pairing channel of electrons in CuO planes due to lateral vibrations of the apical oxygen atoms in adjacent the SrO ionic insulator layer is proposed. Similar ionic substrate phonon model was used recently to explain very high Tc in novel one unit cell F eSe on perovskite STO. A microscopic vibration theory identifies the 40mev phonon mode coupled to conducting CuO planes with λ ∼ 0, 5. It naturally explain the kink in dispersion relation observed by ARPES and the and effect of the isotope substitution. To describe the pseudogap physics by a single band fourfold symmetric t − t Hubbard model, the hopping parameters t ∼ −0.18t and the on side repulsion energy U ∼ 1.9t are chosen. The electronic system is still strongly correlated, but U is weak enough to be effectively described by the mean field model and its perturbative extensions. In particular the fragmentation of the Fermi surface in underdoped samples and the non-circularity of the Fermi Surface are described well within the "symmetrized Hartree -Fock" approximation. The T * transition line dividing the pseudogap (locally antiferromagnetic) and paramagnetic phases and susceptibility (describing spin fluctuations coupling to 2DEG) are also obtained within this approximation. The superconducting gap was calculated in the framework of the weak coupling approximation for both the phonon and the spin fluctuations channels. The dominant "glue" responsible for the d -wave pairing is the phonon mode rather than spin fluctuations, although the later enhances superconductivity by 10-15%. The dependence of the superconducting gap and certain normal state properties, like the kink in dispertion relation,on doping, temperature and effect of the O 16 → O 18 isotope substitution are obtained.

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Section: Appendix C Derivation Of the Gap Equation In Underdoped Systemmentioning

confidence: 99%

Apical oxygen vibrations dominant role in d-wave cuprate superconductivity and its interplay with spin fluctuations

Rosenstein¹,

Shapiro²

2020

Preprint

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“…We derive the Gorkov's equations within the functional integral approach [36,37] starting from the effective electron action Eqs. ( 9), (13) for grassmanian fields ψ * σA k,n and ψ σA k,n :…”

Section: Appendix B Derivation Of Gorkov Equations For a Two Band Systemmentioning

confidence: 99%

Soft phonons in the interface layer of the STO substrate can explain high temperature superconductivity in one unit cell FeSe

Rosenstein,

Shapiro

2019

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Using a microscopic model of lattice vibrations in the STO(001) substrate, an additional Ωs = 50mev longitudinal optical (LO) interface mode is identified. The soft mode propagating mainly in the first T iO2 layer ("O chains") has stronger electron -phonon coupling to electron gas in F eSe than a well known Ω h = 100mev hard mode. The coupling constant, critical temperature, replica band are calculated. Although there exists a forward in the electron -phonon scattering peak, it is clearly not as sharp as assumed in recent theories (delta function -like). The critical temperature is obtained by solution of the gap equation and agrees with the observed one. The corresponding electron phonon coupling constant λ = 0.23. The quasiparticle normal state "satellite" in spectral weight is broad and its peak appears at frequency much higher than Ωs consistent with observations usually associated with Ω h . Possible relation of the transversal counterpart of the surface LO soft mode with known phonons is discussed.

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Apical oxygen vibrations dominant role in d-wave cuprate superconductivity and its interplay with spin fluctuations

Rosenstein¹,

Shapiro²

2021

J. Phys. Commun.

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Microscopic theory of a high T c cuprate Bi 2 Sr 2 CaCu 2 O 8+x based on main pairing channel of electrons in CuO planes due to 40mev lateral vibrations of the apical oxygen atoms in adjacent the SrO ionic insulator layer is proposed. The separation between the vibrating charged atoms and the 2D electron gas creates the forward scattering peak leading in turn to the d -wave pairing within Eliashberg formalism. The phonon mode naturally explain the kink in dispersion relation observed by ARPES and the and effect of the O 16 → O 18 isotope substitution in the normal state. To describe the pseudogap physics a single band fourfold symmetric t − t ′ Hubbard model, with the hopping parameters t ′ ∼ − 0.17 t and the on site repulsion e U ∼ 6t. It described the Mott insulator at low doping, while at higher dopping the pseudogap physics (still strongly correlated) can be be approximated by the symmetrized mean field model and with renormalized U incorporating screening. The location of the transition line T *between the locally antiferromagnetic pseudogap and the paramagnetic overdoped phases and susceptibility (describing spin fluctuations coupling to 2DEG) are also obtained within this approximation. The superconducting d - wave gap mainly due to the phonon channel but is assisted by the spin fluctuations (15%–20%). The dependence of the gap and T c on doping and effect of the isotope substitution are obtained and is consistent with experiments.

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Chiral universality class of normal-superconducting and exciton condensation transitions on surface of topological insulator

Cited by 4 publications

References 98 publications

Apical oxygen vibrations dominant role in d-wave cuprate superconductivity and its interplay with spin fluctuations

Apical oxygen vibrations dominant role in d-wave cuprate superconductivity and its interplay with spin fluctuations

Soft phonons in the interface layer of the STO substrate can explain high temperature superconductivity in one unit cell FeSe

Apical oxygen vibrations dominant role in d-wave cuprate superconductivity and its interplay with spin fluctuations

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