Strain-tunable electronic and magnetic properties of two-dimensional gallium nitride with vacancy defects

Based on density functional theory, we have investigated the effects of in-plane biaxial strain on the electronic and magnetic properties of the two-dimensional GaN (2D GaN) with Ga- (V_Ga) or N-vacancy (V_N). We considered two different levels of vacancy concentration, i.e., $θ=1/62$ and $θ=1/34$⁠. While the pristine GaN 2D structures are intrinsically semiconducting, the 2D GaN with V_Ga defects under tensile/compressive biaxial strains is metallic, except at a high compressive strain of 6%. In addition, the 2D GaN exhibits a strain-tunable magnetic property by introducing the V_Ga defects, where the magnetic moment can be modulated by applying a biaxial strain on the material. A compressive strain larger than 2% tends to suppress the magnetic effect. A drastic reduction of the total magnetization from 2.21 $μB$ to 0.16 $μB$ is clearly visible for a lower V_Ga concentration of $θ=1/62$⁠. On the other hand, the 2D GaN with V_N defects is nonmagnetic, and this behavior is not affected by the biaxial strain.