Publisher's Note: Pairing symmetry of the one-band Hubbard model in the paramagnetic weak-coupling limit: A numerical RPA study [Phys. Rev. B<b>92</b>, 104505 (2015)]

Rømer, Astrid T.; Kreisel, Andreas; Eremin, I.; Malakhov, M. A.; Maier, Thomas; Hirschfeld, P. J.; Andersen, Brian M.

doi:10.1103/physrevb.94.059902

Cited by 3 publications

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“…8 (c,d,g,h), we also tend to have unusually extended pairing with larger numbers of nodes. In the literature, the random-phase approximation (RPA) has been used to obtain the filling-dependent gap symmetry in the t-t model 41 , but the present results exhibit different bahavior such as an absence of s-waves seen in RPA, which should be due to the self-energy effects incorporated more accurately here. For the PFB model, triplet gap functions are close to a simple p-wave, ∆ triplet (k) ∼ sin(k x ) ± sin(k y ), but extra nodes are visible.…”

Section: Resultsmentioning

confidence: 67%

Pairing and non-Fermi liquid behavior in partially flat-band systems: Beyond nesting physics

et al. 2020

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While many-body effects in flat-band systems are receiving renewed hot interests in condensed-matter physics for superconducting and topological properties as well as for magnetism, studies have primarily been restricted to multiband systems (with coexisting flat and dispersive bands). Here we focus on one-band systems where a band is "partially flat" comprising flat and dispersive portions in k-space to reveal whether intriguing correlation effects can arise already on the simplest possible one-band level. For that, the two-dimensional repulsive Hubbard model is studied for two models having different flat areas, in an intermediate-coupling regime with the FLEX+DMFT (the dynamical mean-field theory combined with the fluctuation exchange approximation). We have a crossover from ferromagnetic to antiferromagnetic spin fluctuations as the band filling is varied, and this triggers, for the model with a wider flat portion, a triplet-pair superconductivity favored over an unusually wide filling region, which is taken over by a sharply growing singlet pairing. For the model with a narrower flat portion, TC against filling exhibits an unusual double-peaked Tc dome, associated with different numbers of nodes in the gap function having remarkably extended pairs in real space. We identify these as a manifestation of the physics outside the conventional nesting physics where only the pair scattering across the Fermi surface in designated (hot) spots is relevant. Another correlation effect arising from the flattened band is found in a non-Fermi-liquid behavior as detected in the momentum distribution function, frequency dependence of the self-energy and spectral function. These indicate that unusual correlation physics can indeed occur in flat-band systems.

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Section: Resultsmentioning

confidence: 67%

Pairing and non-Fermi liquid behavior in partially flat-band systems: Beyond nesting physics

et al. 2020

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“…It has been known that the gap symmetry (for the leading eigenvalue) tends to be changed for higher doping or more frustrated cases 36 . The present result suggests that the T SC c enhancement arising from the distortion tends to occur around the boundary for the gap symmetry to change where the leading and sub-leading eigenvalues are close to each other.…”

Section: B Superconductivity Under Fermi Surface Distortionsmentioning

confidence: 99%

Interplay of Pomeranchuk instability and superconductivity in the two-dimensional repulsive Hubbard model

2017

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Interplay of Pomeranchuk instability (spontaneous symmetry breaking of the Fermi surface) and dwave superconductivity is studied for the repulsive Hubbard model on the square lattice with the dynamical mean field theory combined with the fluctuation exchange approximation (FLEX+DMFT). We show that the four-fold symmetric Fermi surface becomes unstable against a spontaneous distortion into two-fold near the van Hove filling, where the symmetry of superconductivity coexisting with the Pomeranchuk-distorted Fermi surface is modified from the d-wave pairing to (d + s)-wave. By systematically shifting the position of van Hove filling with varied second-and third-neighbor hoppings, we find that the transition temperature T PI c for the Pomeranchuk instability is more sensitively affected by the position of van Hove filling than the superconducting T SC c . This implies that the filling region for strong Pomeranchuk instability and that for the T SC c dome can be separated, and that Pomeranchuk instability can appear even if the peak of T PI c is lower than the peak of T SC c . An interesting finding is that the Fermi surface distortion can enhance the superconducting T SC c in the overdoped regime, which is explained with a perturbational picture for small distortions.

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“…Close to critical electron doping, the emergence of hole pockets at (or close to) the Fermi level around ( π 2 , π 2 ), (− π 2 , π 2 ) may occur. 6 Theoretically, the study of spin-fluctuation pairing for the electron-doped cuprates has been addressed mostly in the paramagnetic phase, [7][8][9][10][11][12][13] where the mechanism was found to give rise to a gap with d x 2 −y 2 symmetry with strong non-monotonic features as a function of momentum as a result of Fermi surface intersections with the magnetic zone boundary, the so-called hot spots. At these positions the pairing becomes particularly pronounced.…”

Section: Introductionmentioning

confidence: 99%

“…First, for the paramagnetic phase Scalapino et al 21 generalised the approach of Berk and Schrieffer 22 and found a dominant d x 2 −y 2 -wave pairing instability. Later, the study was extended by various methods and numerical approaches 13,[23][24][25][26][27] including discussions of the possibility of other superconducting pairing symmetries arising from spin fluctuations. From a strong coupling approach, as derived from the t − J model, analysis of the effective pairing at low hole doping 28 suggests a d-wave superconducting ground state in any coexistence phase.…”

Section: Introductionmentioning

confidence: 99%

Superconducting phase diagram of itinerant antiferromagnets

et al. 2016

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We study the phase diagram of the Hubbard model in the weak-coupling limit for coexisting spin-density-wave order and spin-fluctuation-mediated superconductivity. Both longitudinal and transverse spin fluctuations contribute significantly to the effective interaction potential, which creates Cooper pairs of the quasi-particles of the antiferromagnetic metallic state. We find a dominant $d_{x^2-y^2}$-wave solution in both electron- and hole-doped cases. In the quasi-spin triplet channel, the longitudinal fluctuations give rise to an effective attraction supporting a $p$-wave gap, but are overcome by repulsive contributions from the transverse fluctuations which disfavor $p$-wave pairing compared to $d_{x^2-y^2}$. The sub-leading pair instability is found to be in the $g$-wave channel, but complex admixtures of $d$ and $g$ are not energetically favored since their nodal structures coincide. Inclusion of interband pairing, in which each fermion in the Cooper pair belongs to a different spin-density-wave band, is considered for a range of electron dopings in the regime of well-developed magnetic order. We demonstrate that these interband pairing gaps, which are non-zero in the magnetic state, must have the same parity under inversion as the normal intraband gaps. The self-consistent solution to the full system of five coupled gap equations give intraband and interband pairing gaps of $d_{x^2-y^2}$ structure and similar gap magnitude. In conclusion, the $d_{x^2-y^2}$ gap dominates for both hole and electron doping inside the spin-density-wave phase.Comment: 14 pages, 9 figure

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Publisher's Note: Pairing symmetry of the one-band Hubbard model in the paramagnetic weak-coupling limit: A numerical RPA study [Phys. Rev. B92, 104505 (2015)]

Cited by 3 publications

References 0 publications

Pairing and non-Fermi liquid behavior in partially flat-band systems: Beyond nesting physics

Pairing and non-Fermi liquid behavior in partially flat-band systems: Beyond nesting physics

Interplay of Pomeranchuk instability and superconductivity in the two-dimensional repulsive Hubbard model

Superconducting phase diagram of itinerant antiferromagnets

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