Rational Design of Two-Dimensional Magnetic Chromium Borides Based on First-Principles Calculation

Two-dimensional (2D) magnetic materials have been experimentally recognized recently, however, the Curie temperatures ( T C ) of known 2D systems are quite low. Generally, magnetic systems can be seen as constituent magnetic elements providing spins and the non-magnetic elements providing frameworks to host the magnetic elements. Short bond lengths between the magnetic and non-magnetic elements would be beneficial for strong magnetic interactions and thus high T C . Based on this, we propose to combine the magnetic element Cr and the non-magnetic element boron to design novel 2D magnetic systems. Using our self-developed software package IM 2 ODE, we design a series of chromium-boride based 2D magnetic materials. Nine stable magnetic systems are identified. Among them, we find that CrB 4 -I, CrB 4 -II and CrB 5 -I with common structural units [CrB 8 ] are ferromagnetic metals with estimated T C of 270 K, 120 K and 110 K, respectively. On the other hand, five CrB 3 phases with structural units [Cr 2 B 12 ] are antiferromagnetic metals. Additionally, we also find one antiferromagnetic semiconductor CrB 2 -I. Our work may open new directions for identifying 2D magnetic systems with high T C .