Topology and ferroelectricity in group-V monolayers

Rehman Mutee Ur¹, Hua Chenqiang^{1, 2}, Lu Yunhao^{1, 2, ‡}

Two typical stable phases of group-V elements: (a) orthorhombic α phase with space group Cmca, and (b) rhombohedral β phase with space group R3¯m . Left and right panels show side and top views, respectively.