Magnetic response in silicene, germanene, and stanene rings with ferromagnetic and antiferromagnetic exchange fieldNing Xu, Jian Wen Ding, Bao Lin Wang and Heng Yi XuEur. Phys. J. B, 91 11 (2018) 273DOI: https://doi.org/10.1140/epjb/e2018-90281-7