Magnetism of single-walled carbon nanotube with Pd nanowire

Magnetism of single-walled carbon nanotubes (SWNTs) filled with Pd in pseudo one-dimension is investigated based on the electronic structure obtained using the first-principle calculation. In addition, the stability of Pd nanowire inside SWNT is evaluated through the calculation of binding energy. The Pd monostrand nanowire with the inter-atomic distance of 2.49 Å, which shows ferromagnetism in the free-standing state, has the ferromagnetic moment also in the armchair type SWNTs with the diameter lager than 6.9 Å although the magnetic moment is smaller than that of the corresponding free-standing Pd nanowire. The pseudo one-dimensional fcc Pd nanowire with the cross section of the (111) plane in the (14, 0) SWNT has ferromagnetic moment, where the inter-atomic distance is elongated by 28% along the longitudinal axis of SWNT compared with the equilibrium distance, so as to adjust the unit cell size of SWNT. However, the Pd(100) nanowire in (8, 8) SWNT does not show ferromagnetism although it has almost the same inter-atomic distance as that of the (111) nanowire in (14, 0) SWNT. This can be interpreted by means of the magnetism of planar Pd clusters whose laminating composes the nanowire.