Magnetic properties of Ni doped gallium nitride with vacancy induced defect

Abstract

Investigations have been carried out to study the ferromagnetic properties of transition metal (TM) doped wurtzite GaN from first principle calculations using tight binding linear muffin-tin orbital (TBLMTO) method within the density functional theory. The present calculation reveals ferromagnetism in nickel doped GaN with a magnetic moment of 1.13 μ B for 6.25% of Ni doping and 1.32 μ B for 12.5% of nickel doping, there is a decrease of magnetic moment when two Ni atoms are bonded via nitrogen atom. The Ga vacancy ( V Ga) induced defect shows ferromagnetic state. Here the magnetic moment arises due to the tetrahedral bonding of three N atoms with the vacancy which is at a distance of 3.689 Å and the other N atom which is at a distance of 3.678 Å .On the other hand the defect induced by N vacancy ( V N) has no effect on magnetic moment and the system shows metallic character. When Ni is introduced into a Ga vacancy ( V Ga) site, charge transfer occur from the Ni ‘d’ like band to acceptor level of V Ga and formed a strong Ni–N bond. In this Ni– V Ga complex with an Ni ion and a Ga defect, the magnetic moment due to N atom is 0.299 μ B .In case of Ni substitution in Ga site with N vacancy, the system is ferromagnetic with a magnetic moment of 1 μ B.