We study the effects of quantum fluctuations on the dynamical generation of a gap and on the evolution of the spin-wave spectra of a frustrated magnet on a triangular lattice with bond-dependent Ising couplings, analog of the Kitaev honeycomb model. The quantum fluctuations lift the subextensive degeneracy of the classical ground-state manifold by a quantum order-by-disorder mechanism. Nearest-neighbor chains remain decoupled and the surviving discrete degeneracy of the ground state is protected by a hidden model symmetry. We show how the four-spin interaction, emergent from the fluctuations, generates a spin gap shifting the nodal lines of the linear spin-wave spectrum to finite energies.
@article{arxiv.1711.02016,
title = {Quantum gap and spin-wave excitations in the Kitaev model on a triangular lattice},
author = {Adolfo Avella and Andrea Di Ciolo and George Jackeli},
journal= {arXiv preprint arXiv:1711.02016},
year = {2018}
}