Fractional (and conventional) excitations on the kagome lattice

As a pivotal model for frustrated magnetism, the kagome lattice antiferromagnet serves as a theoretical platform for exploring different states of spin systems, from conventional magnetic phases to more exotic quantum spin liquids, and their distinctive static and dynamical properties. In this talk, we discuss the characteristic spectral features of different phases on the kagome lattice, computing the dynamical structure factor by means of a variational method based on projected parton wave functions [1]. On the one hand, we study the effect of the Dzyaloshinskii-Moriya interaction, highlighting the strong renormalization of magnon modes and the presence of peculiar features in the continuum, which cannot be captured within a linear-spin wave approximation [2]. On the other hand, we focus on the chiral spin liquid phase stabilized by three-spin interactions [3] and/or long-range couplings [4], which constitute a (bosonic) lattice version of the fractional quantum Hall state [5]. Within this phase, we probe the existence and stability of chiral edge modes in the presence of open boundaries.

[1] F. Ferrari, F. Becca, Phys. Rev. X 9, 031026 (2019).

[2] F. Ferrari, S. Niu, J. Hasik, et al, SciPost Phys. 14, 139 (2023).

[3] B. Bauer, L. Cincio, B. P. Keller, et al, Nat. Commun. 5, 5137 (2014).

[4] S.-S. Gong, W. Zhu, D. N. Sheng, Sci. Rep. 4, 6317 (2014)

[5] V. Kalmeyer, R. B. Laughlin, Phys. Rev. Lett. 59, 2095 (1987).

This work has been done in collaboration with S. Niu, J. Hasik, Y. Iqbal, D. Poilblanc.