Adsorption-site-dependent magnetic and electronic properties for single- or double-fluorine-atom adsorbed boron nitride nanotubes and their possible applications in spin filters

Highlights: • Magnetism can be induced by fluorination of boron nitride nanotube. • Conductance of the nanotubes with two F adatoms closely depends on their positions. • The possible application of the nanotubes in spin filters is proposed. Here, by using the first-principles method, magnetic and electronic properties of (6, 0) boron nitride nanotubes fluorinated with single fluorine atom (SF-BNNT) or double fluorine atoms (DF-BNNTs) have been investigated. The numerical results show that the non-magnetic and semiconducting BNNT turns to be ferromagnetic and half metallic after a single fluorine atom adsorption. For DF-BNNTs, all the adsorption configurations show ferromagnetic features. However, the electronic properties of DF-BNNTs are closely dependent on adsorption sites of the F adatoms for DF-BNNTs. With different adsorption configurations, DF-BNNTs can be semiconductors, half metals or even conductors. The spin-dependent current-voltage curves of two-probe devices constructed by SF-BNNT or DF-BNNTs indicate that some of the devices manifest high spin filtering efficiency, which can be attributed to the overlap change for the spin-resolved energy bands of two electrodes. This work is helpful for applications of the BNNT in molecular spintronics.