功能化氮化硼纳米管磁性的理论研究

Theoretical Study on the Magnetic Properties of Functionalized Boron Nitride Nanotubes

本文采用密度泛函理论计算研究了氢化/氟化BN纳米管的自发磁化现象.研究结果表明:单个H原子/F原子倾向于吸附在B位,且均能够诱导自发磁化.两个H原子/F原子吸附在B位上时也可以使体系发生自发磁化,而具有磁性的氢化BN纳米管是一种亚稳结构.与此相反,具有磁性的氟化BN纳米管是稳定结构,其磁矩随着覆盖率的增加而增大,其电子学性质与氟原子在BN纳米管表面的覆盖结构有关.因此,具有磁性的氟化BN纳米管比氢化BN纳米管在实验上更容易实现.可以预见,磁性氟化BN纳米管将在自旋电子器件的制作中发挥巨大的应用价值.

Ab initio calculations have been performed to investigate the magnetic properties of hydrogenated boron nitride nanotubes（H-BNNTs） and fluorinated boron nitride nanotubes（F-BNNTs）.It is found that the adsorption of a single H or F atom on B site is more stable than that on N site and induces spontaneous magnetization in the functionalized BNNTs.The adsorptions of two H or F atoms on the external surface of BNNT can also induce spontaneous magnetization,whereas no magnetism is observed in hydrogenated BNNT with two H atoms adsorbed on two neighboring B and N atoms,which is the most stable structure in all structures of hydrogenated BNNTs.Spontaneous magnetism is also found in fluorinated BNNTs at high F coverage and the magnetic moment increases with the increasing F coverage.Compared to hydrogenated BNNTs,fluorinated BNNTs can be easily synthesized and will have good potential in building spintronic devices.