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arXiv · 2502.07884

Magnetic order through Kondo coupling to quantum spin liquids

M. A. Keskiner·M. Ö. Oktel·Natalia B. Perkins·Onur Erten
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Abstract

We study the emergence of magnetic order in localized spins that interact solely through their coupling to a Kitaev-type spin liquid. Using three toy models -- the Kitaev model, the Yao-Lee model, and a square-lattice generalization of the Kitaev model -- we calculate the effective exchange Hamiltonians mediated by the fractionalized excitations of these spin liquids. This setup is analogous to a Kondo lattice model, where conduction electrons are replaced by itinerant Majorana fermions. In the Kitaev model, our results show that the lowest-order perturbation theory generates short-range interactions with modified couplings and extending to sixth order introduces longer-range interactions while preserving the quantum spin-liquid ground state. Models involving more Majorana flavors on honeycomb and square lattices exhibit more complex behavior. The honeycomb Yao-Lee model with three flavors of itinerant Majorana fermions generates long-range RKKY-type interactions, leading to antiferromagnetic order and partial gapping of the Majorana fermion spectrum. In contrast, the square-lattice model produces a combination of anisotropic short- and long-range interactions, which can give rise to either a dimerized quantum paramagnetic state or an Ising antiferromagnet, depending on the parameters. These results illustrate the rich variety of magnetic orders that can be mediated by Kitaev-type spin liquids.

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M. A. Keskiner, M. Ö. Oktel, Natalia B. Perkins, Onur Erten. 2025-02-11. Magnetic order through Kondo coupling to quantum spin liquids. https://doi.org/10.1016/j.mtquan.2025.100038

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