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Condensed Matter > Strongly Correlated Electrons
Title: Spin-phonon interactions on the kagome lattice: Dirac spin liquid versus valence-bond solids
(Submitted on 16 Nov 2023 (v1), last revised 18 Apr 2024 (this version, v2))
Abstract: We investigate the impact of the spin-phonon coupling on the S=1/2 Heisenberg model on the kagome lattice. For the pure spin model, there is increasing evidence that the low-energy properties can be correctly described by a Dirac spin liquid, in which spinons with a conical dispersion are coupled to emergent gauge fields. Within this scenario, the ground-state wave function is well approximated by a Gutzwiller-projected fermionic state [Y. Ran, M. Hermele, P.A. Lee, and X.-G. Wen, Phys. Rev. Lett. 98, 117205 (2007)]. However, the existence of U(1) gauge fields may naturally lead to instabilities when small perturbations are included. Since phonons are ubiquitous in real materials, they may play a relevant role in the determination of the actual physical properties of the kagome antiferromagnet. We perform a step forward in this direction, including phonon degrees of freedom (at the quantum level) and applying a variational approach based upon Gutzwiller-projected fermionic Ans\"atze. Our results suggest that the Dirac spin liquid is stable for small spin-phonon couplings, while valence-bond solids are obtained at large couplings. Even though different distortions can be induced by the spin-phonon interaction, the general aspect is that the energy is lowered by maximizing the density of perfect hexagons in the dimerization pattern.
Submission history
From: Francesco Ferrari [view email][v1] Thu, 16 Nov 2023 11:49:53 GMT (4410kb,D)
[v2] Thu, 18 Apr 2024 11:29:08 GMT (4411kb,D)
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