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

Abstract

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 IM2ODE, we design a series of chromium-boride based 2D magnetic materials. Nine stable magnetic systems are identified. Among them, we find that CrB4-I, CrB4-II and CrB5-I with common structural units [CrB8] are ferromagnetic metals with estimated T C of 270 K, 120 K and 110 K, respectively. On the other hand, five CrB3 phases with structural units [Cr2B12] are antiferromagnetic metals. Additionally, we also find one antiferromagnetic semiconductor CrB2-I. Our work may open new directions for identifying 2D magnetic systems with high T C.