Comparison of electronic and magnetic properties of Fe, Co and Ni nanowires encapsulated in beryllium oxygen nanotubes

The structure, electronic and magnetic properties of transition metals M9 (M = Fe, Co or Ni) nanowires encapsulated inside armchair (8,8) beryllium oxygen nanotube (BeONT) [M9@(8,8)] have been investigated by first-principles calculations. Due to strong interaction between inner M9 nanowire and outer BeONT, not only a near square cross-section shape is formed for outer BeONT but also a counter-clockwise rotation about their common axis takes place for the M9 nanowire. The charge density accumulated strongly around the O atom implies a large charge transfer from Fe atom (as well as from Be atom) to O atom and thus the ionic-binding characters exist among them. The negative values of the binding energies for all three M9@(8,8) hybrid systems indicate the combining processes of all three M9@(8,8) hybrid systems are exothermic. Therefore, the stable insulator (8,8) BeONT can be used to shield the M9 nanowire. Although (8,8) BeONT is non-magnetic and a decrease in the magnetic moments is found after M9 nanowires are encapsulated inside (8,8) BeONT, less than ten percent reduction in the magnetic moments shows all three M9@(8,8) hybrid systems can be utilized in spin transport devices.