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arXiv · 1807.08202

Kondo Breakdown via Fractionalization in a Frustrated Kondo Lattice Model

Johannes S. Hofmann·Fakher F. Assaad·Tarun Grover
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Abstract

We consider Dirac electrons on the honeycomb lattice Kondo coupled to spin-1/2 degrees of freedom on the kagome lattice. The interactions between the spins are chosen along the lines of the Balents-Fisher-Girvin model that is known to host a $\mathbb{Z}_2$ spin liquid and a ferromagnetic phase. The model is amenable to sign free auxiliary field quantum Monte Carlo simulations. While in the ferromagnetic phase the Dirac electrons acquire a gap, they remain massless in the $\mathbb{Z}_2$ spin liquid phase due to the breakdown of Kondo screening. Since our model has an odd number of spins per unit cell, this phase is a non-Fermi liquid that violates the conventional Luttinger theorem which relates the Fermi surface volume to the particle density in a Fermi liquid. This non-Fermi liquid is a specific realization of the so called fractionalized Fermi liquid proposed in the context of heavy fermions. We probe the Kondo breakdown in this non-Fermi liquid phase via conventional observables such as the spectral function, and also by studying the mutual information between the electrons and the spins.

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Johannes S. Hofmann, Fakher F. Assaad, Tarun Grover. 2018-10-31. Kondo Breakdown via Fractionalization in a Frustrated Kondo Lattice Model. https://doi.org/10.1103/physrevb.100.035118

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