Spin-Peierls instabilities of the kagome lattice antiferromagnet*

The spin-1/2 antiferromagnetic Heisenberg model on the kagome lattice is a cornerstone in the field of frustrated magnetism, standing out as one of the most explored magnetic models that could host a quantum spin liquid ground state [1]. The high degree of geometric frustration of the lattice leaves a footprint in the spectrum of the quantum system, which is densely populated by a myriad of singlet excitations, testifying the presence of several proximate competing phases at low-energy, which may be favored by different perturbations. For this reason, we investigate the potential instability of the kagome spin-liquid ground state towards valence-bond order as a consequence of the coupling between spin degrees of freedom and lattice distortions, the latter being modeled by quantum phonons. Employing a recently developed variational Monte Carlo framework [2], we study a (fully quantum) spin-phonon model on the kagome lattice, with an eye to recent experimental findings of structural distortions in the Herbertsmithite compound [3].

[1] L. Savary, L. Balents, Rep. Prog. Phys. 80 016502 (2017)

[2] F. Ferrari, R. Valentí, F. Becca, Phys. Rev. B 104, 035126 (2021)

[3] N.J. Laurita et al, arXiv:1910.13606 (2019)