Electronic and magnetic properties of zigzag GaN nanoribbons with hydrogenation and fluorination

First principles calculations are performed to investigate the electronic and magnetic properties of hydrogenated and fluorinated zigzag GaN nanoribbons (zGaNNRs). Five kinds of possible different hydrogenated structures and four kinds of possible fluorinated structures are considered, and they show various electronic and magnetic properties. We find that the Ga-edges with two hydrogen atoms terminated or two fluorine atoms terminated are ferromagnetic while the N-edges with two hydrogen atoms terminated or two fluorine atoms terminated are nonmagnetic. Results show the structure is half-metal when the Ga-edges are saturated with two fluorine atoms and N-edges saturated with one fluorine atom. The Gibbs free energy of all the considered structures are calculated here to analyze the stability and their relation with chemical potentials. Moreover, the magnetic and electronic properties can be tailored by external electric field. zGaNNRs transform from half-metal to semiconductor under Ga→N direction electric field; it also can change from half-metal to magnetic metal then to nonmagnetic metal under N→Ga direction electric field.