Quantum critical point in the Kondo-Heisenberg model on the honeycomb lattice

Abstract

We study the Kondo--Heisenberg model on the honeycomb lattice at half-filling. Due to the vanishing of the density of states at the fermi level, the Kondo insulator disappears at a finite Kondo coupling even in the absence of the Heisenberg exchange. We adopt a large-N formulation of this model and use the renormalization group machinery to study systematically the second order phase transition of the Kondo insulator (KI) to the algebraic spin liquid (ASL). We note that neither phase breaks any physical symmetry, so that the transition is not described by the standard Ginzburg-Landau-Wilson critical point. We find a stable Lorentz-invariant fixed point that controls this second order phase transition. We calculate the exponent $\nu$ of the diverging length scale near the transition. The quasi-particle weight of the conduction electron vanishes at this KI--ASL fixed point, indicating non-Fermi liquid behavior. The algebraic decay exponent of the staggered spin correlation is calculated at the fixed point and in the ASL phase. We find a jump in this exponent at the transition point.

The published version. New title. Very minor changes in the abstract and introduction compared to the original version

References in corpus (9)

• "Deconfined" quantum critical points
• Quantum criticality beyond the Landau-Ginzburg-Wilson paradigm
• Quantum criticality
• Weak magnetism and non-Fermi liquids near heavy-fermion critical points
• Fractionalized Fermi liquids
• On the stability of U(1) spin liquids in two dimensions
• Algebraic spin liquid as the mother of many competing orders
• Transport anomalies in a simplified model for a heavy electron quantum critical point
• Quantum phase transitions out of the heavy Fermi liquid

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• Pair-density-wave and $s\pm \mathrm{i}d$ superconductivity in a strongly coupled, lightly doped Kondo insulator
• Breakdown of heavy quasiparticles in a honeycomb Kondo lattice: A quantum Monte Carlo study
• Topological antiferromagnetic spin-density-wave phase in an extended Kondo lattice model
• Schwinger boson approach for the dynamical mean-field theory of the Kondo lattice
• SU($\mathbf{N}$) Kondo-Heisenberg chain: Phase diagram, Ising criticality, and the coexistence of heavy quasiparticles and valence bond solid order
• Dynamic-RKKY induced time-reversal symmetry breaking and chiral spin liquids