Two-dimensional antiferromagnetic boron form first principles

A new two-dimensional (2D) antiferromagnetic semiconducting boron structure, named as M-B28, is predicted using ab initio evolutionary structure searching. First-principles calculations show that M-B28 has a lower energy than other 2D magnetic boron structures and is dynamically stable. The unpaired electrons from the caps of B26 clusters lead to magnetism in M-B28, while making its highest valence band flat and isolated. The Néel temperature and mechanical properties of M-B28 are evaluated with the Ising model and strain-stress method, respectively, revealing a transition temperature of 32 K and the ideal strengths of 43.7 N/m along x direction and 38.5 N/m along y direction.