Unconventional Superconductivity from Local Spin Fluctuations in the Kondo Lattice

Bodensiek, Oliver; Žitko, Rok; Vojta, Matthias; Jarrell, Mark; Pruschke, Thomas

doi:10.1103/physrevlett.110.146406

Cited by 47 publications

(44 citation statements)

References 28 publications

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“…Similiar spin resonances also exist in the superconducting phase of the KLM 37 and they share some other common properties, for instance their position also changes linearly with J. These analogies are not too surprising since the Nambu formalism used to describe superconductivity is very similar to the A/B sublattice formalism used to describe Néel order on bipartite lattices, thus the analytical structure of the DMFT self-consistency equations is analogous.…”

Section: Discussionmentioning

confidence: 86%

Fine structure of spectra in the antiferromagnetic phase of the Kondo lattice model

2015

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We study the antiferromagnetic phase of the Kondo lattice model on bipartite lattices at half-filling using the dynamical mean-field theory with numerical renormalization group as the impurity solver, focusing on the detailed structure of the spectral function, self-energy, and optical conductivity. We discuss the deviations from the simple hybridization picture, which adequately describes the overall band structure of the system (four quasiparticle branches in the reduced Brillouin zone), but neglects all effects of the inelastic-scattering processes. These lead to additional structure inside the bands, in particular asymmetric resonances or dips that become more pronounced in the strong-coupling regime close to the antiferromagnet-paramagnetic Kondo insulator quantum phase transition. These features, which we name "spin resonances", appear generically in all models where the f -orbital electrons are itinerant (large Fermi surface) and there is Néel antiferromagnetic order (staggered magnetization), such as periodic Anderson model and Kondo lattice model with antiferromagneitc Kondo coupling, but are absent in antiferromagnetic phases with localized f -orbital electrons (small Fermi surface), such as the Kondo lattice model with ferromagnetic Kondo coupling. We show that with increasing temperature and external magnetic-field the spin resonances become suppressed at the same time as the staggered magnetization is reduced. Optical conductivity σ(Ω) has a threshold associated with the indirect gap, followed by a plateau of low conductivity and the main peak associated with the direct gap, while the spin resonances are reflected as a secondary peak or a hump close to the main optical peak. This work demonstrates the utility of high-spectralresolution impurity solvers to study the dynamical properties of strongly correlated fermion systems.

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Section: Discussionmentioning

confidence: 86%

Fine structure of spectra in the antiferromagnetic phase of the Kondo lattice model

2015

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“…The DMFT treatment allows us to discuss the stability of the s-wave SC state more quantitatively than the static BCS mean-field theory [26]. In fact, the DMFT method has been successfully applied to various strongly correlated fermion systems with SC and superfluid states [27][28][29][30][31][32][33][34].…”

Section: Model and Methodsmentioning

confidence: 99%

Superconductivity in the two-band Hubbard model

Koga

Werner

2015

Phys. Rev. B

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We study the two-band Hubbard model in infinite dimensions by solving the dynamical mean-field equations with a strong coupling continuous-time quantum Monte Carlo method and show that an s-wave superconducting state can be stabilized in the repulsively interacting case. We discuss how this superconducting state competes with the metallic and paired Mott states. The effects of the Hund coupling and crystalline electric field are also addressed.

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“…We perform the same calculations by changing U/U the local density fluctuations of unpaired atoms and the nonlocal CDW fluctuations Recently, s-wave superconductivity driven by local spin fluctuations was found in the paramagnetic sector of the Kondo lattice model [29]. In this study, a question arose concerning the pairing symmetry driven by the competition or cooperation between local and nonlocal fluctuations.…”

Section: Phase Diagram and Discussionmentioning

confidence: 99%

Controlled pairing symmetry of the superfluid state in systems of three-component repulsive fermionic atoms in optical lattices

Suga

2015

Phys. Rev. A

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We investigate the pairing symmetry of the superfluid state in repulsively interacting threecomponent (color) fermionic atoms in optical lattices. When two of the three color-dependent repulsions are much stronger than the other, pairing symmetry is an extended s wave, although the superfluid state appears adjacent to the paired Mott insulator in the phase diagram. On the other hand, when two of the three color-dependent repulsions are weaker than the other, pairing symmetry is a d x 2 −y 2 -wave. This change in pairing symmetry is attributed to the change in the dominant quantum fluctuations from the density fluctuations of unpaired atoms and the color-density wave fluctuations to the color-selective antiferromagnet fluctuations. This phenomenon can be studied using existing experimental techniques.

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Unconventional Superconductivity from Local Spin Fluctuations in the Kondo Lattice

Cited by 47 publications

References 28 publications

Fine structure of spectra in the antiferromagnetic phase of the Kondo lattice model

Fine structure of spectra in the antiferromagnetic phase of the Kondo lattice model

Superconductivity in the two-band Hubbard model

Controlled pairing symmetry of the superfluid state in systems of three-component repulsive fermionic atoms in optical lattices

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