The class of two-interacting-impurity spin-boson models with vanishing transverse fields on the spin-pair is studied. The model can be exactly mapped into two independent standard single-impurity spin-boson models where the role of the tunnelling parameter is played by the spin-spin coupling. The dynamics of the magnetization is analysed for different levels of (an)isotropy. Further, the existence of a decoherence-free subspace as well as of both classical and quantum (first-order and Kosterlitz-Thouless type) phase transitions, in the Omhic regime, is brought to light.
@article{arxiv.2205.09367,
title = {Spin-spin coupling-based quantum and classical phase transitions in two-impurity spin-boson models},
author = {Roberto Grimaudo and Antonino Messina and Hiromichi Nakazato and Alessandro Sergi and Davide Valenti},
journal= {arXiv preprint arXiv:2205.09367},
year = {2022}
}