Tunable electronic and magnetic properties of transition-metal atoms doped CrBr3 monolayer

The CrBr3 monolayer is a two-dimensional semiconductor material with intrinsic ferromagnetism. However, the low Curie temperature of CrBr3 monolayer limits its practical development in innovative spintronic devices. The electronic and magnetic properties of transition-metal atoms doped CrBr3 monolayer have been systematically investigated by using the density functional theory calculations. The formation energy elucidates that all 3d transition metal (TM) atoms prefer to be doped in the middle of a hexagon (H) site of CrBr3 monolayer. And all the TM atoms, except the Zn atom, can bond strongly to the surrounding Cr atoms with sizable formation energy. The results also indicate that the magnetic moment of TM-CrBr3 system changes as a result of the charge transfer between TM atom and adjacent Cr atom. In addition, comparing with the intrinsic CrBr3, the T-C of TM-CrBr3 system increases significantly, which means that the ferromagnetic stability of CrBr3 monolayer is enhanced. In particular, the T-C of CrBr3 with Sc atom can be increased by 159%. The enhancement of ferromagnetism is mainly due to the competition between the direct exchange and the superexchange interaction. We also find that the electronic properties of the TM-CrBr3 systems are diverse. For example, Sc-, Ti-, V-, Mn-, Fe-, Co-, Ni-, Cu- and Zn-CrBr3 exhibit spin gapless semiconductor (SGS) properties with 100% spin polarization at Fermi level. The TM-CrBr3 system can be adjusted from semiconductor to half-metal when Cr atoms are doped into the CrBr3 monolayer. This work, together with recent achievements in the field of two-dimensional ferromagnetic materials, provides an experimentally achievable guide for realizing the preparation of TM-CrBr3 system with high Curie temperature. Moreover, the possibility of application of these systems in nanoelectronics and spintronics is increased.