Vacancy Induced Magnetism and Spin Filtering in 2D GaN Monolayer

Abstract

Exotic properties functionalized by Ga or N atom vacancies in two-dimensional GaN monolayer have been predicted for the first time. A detailed ab-initio study of the structural, electronic, magnetic and optical properties of a 2D–GaN monolayer containing Ga or N atom vacancies has been performed.  In the present study, we make two refinements in the density functional theory.  At first, long range dispersion interactions not discussed so far have been accounted for. Further, norm-conserving pseudopotentials and plane waves are employed in generalized gradient approximation in contrast to earlier workers who have used soft or ultra-soft pseudopotentials. One observes that the strength of induced magnetism depends not on the separation of Ga-vacancies but on the number of Ga atom vacancies. The magnetism induced by N-atom vacancies is either zero or quite small. Spin filtering has been observed in many configurations. A strong continuous absorption from the far infrared region to the deep visible region is seen in some systems. It may be useful for development of photo-emitting devices which will emit in various regions of energy spectrum including visible emission. The emission of 2D-GaN monolayer lying in deep ultraviolet region may be used for sterilization, water purification etc.