The relation between unusual Mexican-hat band dispersion, ferromagnetism and ferroelasticity is investigated using a combination of analytical, first-principles and phenomenological methods. The class of material with Mexican-hat band edge is studied using the α-SnO monolayer as a prototype. Such band edge causes a van Hove singularity diverging with E1, and in p-type material leads to spatial and/or time-reversal spontaneous symmetry breaking. We show that an unexpected multiferroic phase is obtained in a range of hole density for which the material presents ferromagnetism and ferroelasticity simultaneously.
@article{arxiv.1601.06438,
title = {Multiferroic Two-Dimensional Materials},
author = {L. Seixas and A. S. Rodin and A. Carvalho and A. H. Castro Neto},
journal= {arXiv preprint arXiv:1601.06438},
year = {2016}
}