Unconventional Fermi Surface Instabilities in the Kagome Hubbard Model

Kiesel, Maximilian L.; Platt, Christian; Thomale, Ronny

doi:10.1103/physrevlett.110.126405

Cited by 424 publications

(339 citation statements)

References 28 publications

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“…This includes the multi-d orbital candidate models for electronically driven Fermi surface instabilities such as pnictides [24,29], ruthenates [37], and sodium doped cobaltates [38] many of which are addressed in this review, but also Hubbard models on unconventional lattices such as doped graphene [39,40] or itinerant electron orderings on the kagome lattice [41], which will likewise be discussed in the following.…”

Section: Advances In Physicsmentioning

confidence: 99%

“…4.3 discusses long-range Hubbard interactions on the tight-binding kagome lattice [41]. As opposed to the honeycomb lattice, it features three sublattices, which turns out to be of fundamental importance to characterize its Fermi surface instabilities.…”

Section: Advances In Physics 59mentioning

confidence: 99%

“…It should be noted that the subtle interplay of competing fluctuations makes the kagome Hubbard model a challenging problem for FRG techniques. At present, different formulations of FRG have given largely similar, but partly also conflicting results [41,219]. (A more detailed discussion is contained in Ref.…”

Section: Sublattice Interference: Kagome Vs Honeycomb Latticementioning

confidence: 99%

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Functional renormalization group for multi-orbital Fermi surface instabilities

Platt

Hanke

Thomale

2013

Advances in Physics

196

253

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Technological progress in material synthesis, as well as artificial realization of condensed matter scenarios via ultra-cold atomic gases in optical lattices or epitaxial growth of thin films, is opening the gate to investigate a plethora of unprecedented strongly correlated electron systems. In a large subclass thereof, a metallic state of layered electrons undergoes an ordering transition below some temperature into unconventional states of matter driven by electronic correlations, such as magnetism, superconductivity, or other Fermi surface instabilities. While this type of phenomena has been a well-established direction of research in condensed matter for decades, the variety of today's accessible scenarios pose fundamental new challenges to describe them. A core complication is the multi-orbital nature of the low-energy electronic structure of these systems, such as the multi-d orbital nature of electrons in iron pnictides and transition-metal oxides in general, but also electronic states of matter on lattices with multiple sites per unit cell such as the honeycomb or kagome lattice. In this review, we propagate the functional renormalization group (FRG) as a suited approach to investigate multi-orbital Fermi surface instabilities. The primary goal of the review is to describe the FRG in explicit detail and render it accessible to everyone both at a technical and intuitive level. Summarizing recent progress in the field of multi-orbital Fermi surface instabilities, we illustrate how the unbiased fashion by which the FRG treats all kinds of ordering tendencies guarantees an adequate description of electronic phase diagrams and often allows to obtain parameter trends of sufficient accuracy to make qualitative predictions for experiments. This review includes detailed and illustrative illustrations of magnetism and, in particular, superconductivity for the iron pnictides from the viewpoint of FRG. Furthermore, it discusses candidate scenarios for topological bulk singlet superconductivity and exotic particle-hole condensates on hexagonal lattices such as sodium-doped cobaltates, graphene doped to van Hove filling, and the kagome Hubbard model. In total, the FRG promises to be one of the most versatile and revealing numerical approaches to address unconventional Fermi surface instabilities in future fields of condensed matter research.

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Section: Advances In Physicsmentioning

confidence: 99%

Section: Advances In Physics 59mentioning

confidence: 99%

Section: Sublattice Interference: Kagome Vs Honeycomb Latticementioning

confidence: 99%

See 1 more Smart Citation

Functional renormalization group for multi-orbital Fermi surface instabilities

Platt

Hanke

Thomale

2013

Advances in Physics

196

253

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“…The vanishing couplings between the saddle points are related to the nontrivial sublattice interference discussed in Refs. [38,39]. Although the susceptibility at the three Q η still has a logarithmic divergence (instead of log 2 ) due to the divergent DOS at the saddle points, the triple-Q spin order now has to compete with simple ferromagnetism instability which also results from a divergent DOS.…”

Section: Van Hove Filling F = 5/12mentioning

confidence: 99%

Exotic magnetic orderings in the kagome Kondo-lattice model

et al. 2014

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We consider the Kondo-lattice model on the kagome lattice and study its weak-coupling instabilities at band filling fractions for which the Fermi surface has singularities. These singularites include Dirac points, quadratic Fermi points in contact with a flat band, and Van Hove saddle points. By combining a controlled analytical approach with large-scale numerical simulations, we demonstrate that the weak-coupling instabilities of the Kondo-lattice model lead to exotic magnetic orderings. In particular, some of these magnetic orderings produce a spontaneous quantum anomalous Hall state.

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“…By loading fermionic dipolar atoms [19] and molecules [20][21][22] onto optical lattices, unconventional density-wave instabilities may arise from the long-range and anisotropic dipole-dipole [23][24][25][26] or quadrupolar [27] interactions. By creating a Kagome optical lattice [28], a bond order wave can be stabilized,resulting from sublattice interference effects [29], in the presence of a sufficiently large nearestneighbor repulsive term [30,31].…”

Section: Introductionmentioning

confidence: 99%

dxy-density wave in fermion-fermion cold-atom mixtures

Lai

Campbell

et al. 2014

Phys. Rev. A

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We study density wave instabilities in a doubly-degenerate Fermi-Fermi mixture with SU (2) × SU (2) symmetry on a square lattice. For sufficiently large on-site inter-species repulsion, when the two species of fermions are both at half-filling, two conventional (s-wave) number density waves are formed with a π-phase difference between them to minimize the inter-species repulsion. Upon moving one species away from half-filling, an unconventional density wave with dxy-wave symmetry emerges. When both species are away from the vicinity of half-filling, superconducting instabilities dominate. We present results of a functional renormalization-group calculation that maps out the phase diagram at weak couplings. Also, we provide a simple explanation for the emergence of the dxy-density wave phase based on a four-patch model. We find a robust and general mechanism for dxy-density-wave formation that is related to the shape and size of the Fermi surfaces. The density imbalance between the two species of fermions in the vicinity of half-filling leads to phasespace discrepancy for different inter-species Umklapp couplings. Using a phase space argument for leading corrections in the one-loop renormalization group approach to fermions, we show that the phase-space discrepancy in our system causes opposite flows for the two leading intra-species Umklapp couplings and that this triggers the dxy-density-wave instability.

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Unconventional Fermi Surface Instabilities in the Kagome Hubbard Model

Cited by 424 publications

References 28 publications

Functional renormalization group for multi-orbital Fermi surface instabilities

Functional renormalization group for multi-orbital Fermi surface instabilities

Exotic magnetic orderings in the kagome Kondo-lattice model

dxy-density wave in fermion-fermion cold-atom mixtures

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