Magnetic and electronic properties of a single iron atomic chain encapsulated in carbon nanotubes: A first-principles study

Under the generalized gradient approximation (GGA), the magnetic and electronic properties have been investigated for a Fe atom chain wrapped in armchair (n,n) carbon nanotubes (CNTs) (2 ≤ n ≤ 6)) by using the first-principles projector-augmented wave (PAW) potential within the density function theory (DFT) framework. After simply moving the Fe atom chain parallel to tube axis to make Fe atom locates on the perpendicular of the tube wall through the center of a hexagon by carbon-carbon bonds, all Fe@(n,n) systems including the narrow Fe@(2,2) and Fe@(3,3) systems exhibit metallic character and the Fe atom chain maintains its magnetic moment. Total density of states (DOS) and projected densities of states (PDOS) analyses show that the spin polarization and the magnetic moment of Fe@(n,n) systems come mostly from the Fe atom chain. And with increasing n and thus tube diameter, the difference between the minority spin and the majority spin at the Fermi level increases for the PDOS onto Fe atom and thus for the DOS of Fe@(n,n) systems. This trend is also indicated quantitatively by the magnetic moment on Fe atom and spin polarization for Fe@(n,n) systems. The higher magnetic moment and spin polarization of the Fe@(6,6) system show it can be used as magnetic nanostructure possessing potential current and future applications in permanent magnetism, magnetic recording, and spintronics.