Ab initio study on electronic structure and magnetic properties of AlN and BP monolayers with Ti doping

The spintronic properties of Aluminum Nitride (AlN) and Boron Phosphide (BP) monolayers with Titanium (Ti) doping have been studied by using first principles calculation. The Ti-doped AlN monolayer will produce the magnetic moment of 1 μ_B, which is mainly contributed by d orbital of the impurity. Although Ti_P (Phosphorus was replaced by Ti) can lead to semi-metallic properties in BP monolayer, Ti_B (Boron was replaced by Ti) has a lower formation energy. The magnetic moment produced by Ti_B is 1 μ_B, which is also mainly contributed by the Ti-d orbital. The strain studies show that the band gap of AlN monolayer will decrease with the increase of strain, while the pristine BP monolayer increases. Ti_B will make the band gap of BP increase first and then decrease when it is 10%. Studies on magnetic coupling indicate that ferromagnetic and antiferromagnetic coupling oscillations will occur at different Ti-Ti distances in the AlN monolayer. However, Ti_B-Ti_B are always coupled antiferromagnetically at each distance in the BP monolayer. Further study shows that the Néel temperature of the BP system with Ti_B may be higher than room temperature.