Frustrated Kondo impurity triangle: A simple model of deconfinement

Abstract

The concepts of deconfinement and topological order are of great current interest for quantum information science and for our understanding of quantum materials. Here, we introduce a simple model of three antiferromagnetically coupled Kondo impurities, a Kondo triangle, which can be used to further extend the application of these concepts to electronic systems. We show that, by tuning the magnetic frustration, the Kondo triangle undergoes a quantum phase transition between two phases of unbroken symmetry, signaling a phase transition beyond the Landau paradigm. We demonstrate that the frustrated spin liquid phase is described by a three-channel Kondo (3CK) fixed point and thus displays an irrational ground state degeneracy. Using an Abrikosov pseudofermion representation, this quantum state is categorized by an emergent U(1) gauge field and its projective symmetry group. The gauge theory is deconfining in the sense that a miniature Wilson loop orders and topological defects (instantons in the gauge field) are expelled. This phase persists in the presence of moderate Kondo screening until proliferation of topological defects leads to a quantum phase transition to an unfrustrated Fermi liquid phase. Based on this evidence, we propose that the 3CK phase displays topological order in a similar sense as gapless spin liquids.

8 pages with 4 figures + Appendices

References in corpus (23)

• "Deconfined" quantum critical points
• Weak magnetism and non-Fermi liquids near heavy-fermion critical points
• Fractionalized Fermi liquids
• Observation of two-orbital spin-exchange interactions with ultracold SU(N)-symmetric fermions
• Mott Transition from a Spin Liquid to a Fermi Liquid in the Spin-Frustrated Organic Conductor kappa-(ET)2Cu2(CN)3
• On the stability of U(1) spin liquids in two dimensions
• Topological Kondo effect with Majorana fermions
• Orbital-selective Mott transitions: Heavy fermions and beyond
• Stability of the U(1) spin liquid with spinon Fermi surface in 2+1 dimensions
• Spin-split band hybridization in graphene proximitized with $\alpha$-RuCl${}_3$ nanosheets
• Kondo screening in a magnetically frustrated nanostructure: Exact results on a stable, non-Fermi-liquid phase
• Transport anomalies in a simplified model for a heavy electron quantum critical point
• Anyons in Multichannel Kondo Systems
• Kondo-based Qubits for Topological Quantum Computation
• Spin magnetometry as a probe of stripe superconductivity in twisted bilayer graphene
• Signature of frustrated moments in quantum critical CePd${}_{1-x}$Ni${}_x$Al
• Emergent Fermi surface in a triangular-lattice SU(4) quantum antiferromagnet
• The Triplet Resonating Valence Bond State and Superconductivity in Hund's Metals
• Strongly correlated multi-impurity models: The crossover from a single-impurity problem to lattice models
• Soluble limit and criticality of fermions in Z2 gauge theories
• Emergent moments in a Hund's impurity
• Magnetic Kondo regimes in a frustrated half-filled trimer
• Competition between Kondo and Kitaev Physics in Kitaev clusters coupled to a fermionic bath

Cited by in corpus (6)

• Cascade of vestigial orders in two-component superconductors: nematic, ferromagnetic, s-wave charge-4e, and d-wave charge-4e states
• Topological symplectic Kondo effect
• Frustration shapes multi-channel Kondo physics: a star graph perspective
• Few-body precursors of topological frustration
• Spiral magnetism and chiral superconductivity in Kondo-Hubbard triangular lattice model
• Triplet resonating valence bond theory and transition metal chalcogenides