The Effect of Functionalization on Spin-Polarized Transport of Gallium Nitride–Based Magnetic Tunnel Junctions

Using first-principles spin-polarized density functional theory computations, the effect of functionalization (fluorination and hydrogenation) on spin-polarized transport of gallium nitride (GaN) nanosheet–based magnetic tunnel junction (MTJ) with CrO₂ as electrodes is investigated. The results show fluorinated GaN–based structure exhibits better spin filtration and high TMR (maximum ~ 99%), as compared with hydrogenated GaN (maximum TMR ~ 93%)– and pristine GaN (maximum TMR ~ 83%)–based structures. In addition, fluorinated GaN nanosheet exhibits a ferromagnetic behavior with a magnetic movement of 1.0 μ_b per fluorine atom. The magnetic movements for pristine GaN and hydrogenated GaN sheets are reported to be 0 μ_b and 0.9 μ_b per hydrogen atom, respectively. Higher TMR, better spin filtration, and ferromagnetic behavior for fluorinated GaN–based structure open up its possibility as spin filter (injector) in MTJs and other spin-based devices.