We study field-induced phase transitions of the minimal exchange model proposed earlier for BaCo2(AsO4)2, a candidate for Kitaev honeycomb model, using numerical minimization of classical spin clusters. We show that experimentally observed sequence of step-like transitions in magnetic field is realized in the phase diagram of the minimal model. Surprisingly, intermediate up-up-down plateau phase is stabilized only in the proximity of a double-zigzag−zigzag phase boundary. We systematically map out the region of stability of experimentally observed cascade of transitions and argue that BaCo2(AsO4)2 exchange parameters are close to a region of strong phase competition, which can explain suppressed saturation field.
@article{arxiv.2308.10672,
title = {Proximity-induced sequence of field transitions in Kitaev candidate BaCo$_2$(AsO$_4$)$_2$},
author = {Pavel A. Maksimov},
journal= {arXiv preprint arXiv:2308.10672},
year = {2024}
}