Fractionalized Fermi liquids and exotic superconductivity in the Kitaev-Kondo lattice

Seifert, Urban F. P.; Meng, Tobias; Vojta, Matthias

doi:10.1103/physrevb.97.085118

Cited by 38 publications

(34 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the isotropic case, we also tested the spin representation (7) as recently used in Ref. 20 and find qualitative (and semi-quantitative) agreement with the results obtained by using Kitaev's spin representation.…”

Section: A Majorana Representationsupporting

confidence: 58%

“…suitably chosen SO(4) matrices, which are to be understood as the Majorana analogue of the Pauli matrices acting on the spinor (f ↑ , f ↓ ) T . 20 Note that above representation can be seen to be equivalent to Kitaev's representation by employing the Hilbert-space constraint D = 1. The representation (7) admits a redundancy χ → G α χ, where…”

Section: A Majorana Representationmentioning

confidence: 99%

“…however stress that the flat bands do not correspond to the static excitations of the gauge field. 20 Considering the bilayer models, the inter-layer Heisenberg interaction H ⊥ which constitutes a quartic interaction for the Majorana fermions can be decoupled in an analogous manner to (12), yielding the mean-field Hamiltonian…”

Section: B Mean-field Theorymentioning

confidence: 99%

See 2 more Smart Citations

Bilayer Kitaev models: Phase diagrams and novel phases

et al. 2018

Self Cite

View full text Add to dashboard Cite

Kitaev's honeycomb-lattice spin-1/2 model has become a paradigmatic example for Z2 quantum spin liquids, both gapped and gapless. Here we study the fate of these spin-liquid phases in differently stacked bilayer versions of the Kitaev model. Increasing the ratio between the inter-layer Heisenberg coupling J ⊥ and the intra-layer Kitaev couplings K x,y,z destroys the topological spin liquid in favor of a paramagnetic dimer phase. We study phase diagrams as a function of J ⊥ /K and Kitaev coupling anisotropies using Majorana-fermion mean-field theory, and we employ different expansion techniques in the limits of small and large J ⊥ /K. For strongly anisotropic Kitaev couplings, we derive effective models for the different layer stackings which we use to discuss the quantum phase transition out of the Kitaev phase. We find that the phase diagrams depend sensitively on the nature of the stacking and anisotropy strength. While in some stackings and at strong anisotropies we find a single transition between the Kitaev and dimer phases, other stackings are more involved: Most importantly, we prove the existence of two novel macro-spin phases which can be understood in terms of Ising chains which can be either coupled ferromagnetically, or remain degenerate, thus realizing a classical spin liquid. In addition, our results suggest the existence of a flux phase with spontaneous inter-layer coherence. We discuss prospects for experimental realizations. Summary of resultsThe main results can be summarized as follows: Different stackings of the Kitaev x, y, z bonds, yielding different symmetry properties, produce significantly different phase diagrams, as summarized in Fig. 1. These differ-arXiv:1806.01852v2 [cond-mat.str-el]

show abstract

Section: A Majorana Representationsupporting

confidence: 58%

Section: A Majorana Representationmentioning

confidence: 99%

See 1 more Smart Citation

Bilayer Kitaev models: Phase diagrams and novel phases

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Low-temperature properties may or may not be Fermi-liquid-like, depending on whether the emergent excitations of the spin-liquid component are gapped or gapless. Fractionalized Fermi liquids may display a variety of instabilities driven by the strong correlations in the local-moment sector, including unconventional superconductivity [103,105]. ‡ A T 2 behavior of the resistivity requires the existence of Umklapp scattering processes, i.e., a sufficiently large Fermi surface.…”

Section: Fermi Liquids Non-fermi Liquids and Fractionalized Fermi Lmentioning

confidence: 99%

Frustration and quantum criticality

Vojta

2018

Rep. Prog. Phys.

Self Cite

View full text Add to dashboard Cite

This review article is devoted to the interplay between frustrated magnetism and quantum critical phenomena, covering both theoretical concepts and ideas as well as recent experimental developments in correlated-electron materials. The first part deals with local-moment magnetism in Mott insulators and the second part with frustration in metallic systems. In both cases, frustration can either induce exotic phases accompanied by exotic quantum critical points or lead to conventional ordering with unconventional crossover phenomena. In addition, the competition of multiple phases inherent to frustrated systems can lead to multi-criticality.

show abstract

“…Subsequent studies, using perturbative scaling [13,14] as well as more rigorous numerical treatment using the numerical renormalization group [15], have shown the existence of an unstable fixed point that gives rise to a first-order flux transition between the weak-coupling flux-free phase and the strongcoupling impurity-flux phase, upon tuning the coupling between the impurity and the lattice. Other studies have used slave-particle mean field theories to investigate situations involving a Kondo lattice model on the honeycomb lattice with Kitaev interactions among the local moments, giving rise to fractionalized Fermi liquid behavior and exotic superconductivity [16,17]. Here, the effective hybridization of Majorana modes and conduction electrons due to the Kondo effect imprints superconductivity onto the conduction electron system.…”

Section: Introductionmentioning

confidence: 99%

Competition between Kondo physics and Kitaev physics in Kitaev clusters coupled to a fermionic bath

2020

View full text Add to dashboard Cite

Geometrically frustrated quantum impurities coupled to metallic leads have been shown to exhibit rich behavior with a quantum phase transition separating Kondo screened and local moment phases. Frustration in the quantum impurity can alternatively be introduced via Kitaev-couplings between different spins of the impurity cluster. We use the Numerical Renormalization Group (NRG) to study a range of systems where the quantum impurity comprising a Kitaev cluster is coupled to a bath of non-interacting fermions. The models exhibits a competition between Kitaev and Kondo dominated physics depending on whether the Kitaev couplings are greater or less than the Kondo temperature. We characterize the ground state properties of the system and determine the temperature dependence of the crossover scale for the emergence of fractionalized degrees of freedom in the model. We also demonstrate qualitatively as well as quantitatively that in the Kondo limit, the complex impurity can be mapped to an effective two-impurity system, where the emergent spin 1/2 comprises of both Majorana and flux degrees of freedom. For a tetrahedral-shaped Kitaev cluster, an extra orbital degree of freedom closely related to a flux degree of freedom remains unscreened even in the presence of both Heisenberg and Kondo interactions.

show abstract

Fractionalized Fermi liquids and exotic superconductivity in the Kitaev-Kondo lattice

Cited by 38 publications

References 54 publications

Bilayer Kitaev models: Phase diagrams and novel phases

Bilayer Kitaev models: Phase diagrams and novel phases

Frustration and quantum criticality

Competition between Kondo physics and Kitaev physics in Kitaev clusters coupled to a fermionic bath

Contact Info

Product

Resources

About