The spin-3/2 Heisenberg antiferromagnet on the bilayer honeycomb lattice is a minimal model to describe the magnetic behavior of Bi3Mn4O12(NO3). We study this model with frustrating inter-layer second-neighbor couplings, taking into account quantum and thermal fluctuations. We use a path integral formulation in terms of coherent states to describe the low energy physics of the model. We show that for a particular point in the parameter space, close to the experimental estimated couplings, a continuum classical degeneracy is lifted by both quantum and thermal fluctuations, and a collinear state is then selected by an order by disorder mechanism. Our results provide a global perspective in the understanding of the experimental observations.
@article{arxiv.2109.11687,
title = {An effective field theory approach for the $S = 3/2$ bilayer honeycomb antiferromagnet},
author = {S. Acevedo and C. A. Lamas and P. Pujol},
journal= {arXiv preprint arXiv:2109.11687},
year = {2021}
}