Comparison of the structural, electronic and magnetic properties of Fe, Co and Ni nanowires encapsulated into silicon carbide nanotube

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A similar optimized structure, i.e. a near square cross-section shape for outside nanotube and a relative rotation between nanowire and its outside nanotube, is obtained for the transition-metal M13 (M = Fe, Co, Ni) nanowires with the FCC structure encapsulated inside the armchair (8, 8) silicon carbide nanotube [ M13@(8, 8)] . It is also found that the stabilities of M13 nanowires are enhanced by silicon carbide nanotube encapsulation. Although the spin polarization P of each hybrid system is slightly lowered with respect to the corresponding free-standing nanowire, the largest spin polarization value 71% of Co13@(8, 8) among the three hybrid systems suggests it could be utilized to construct efficient spin transport devices. As compared with the corresponding free-standing nanowire, the magnetic moments μ1 and μ2 for the peripheral M1 (especially) and M2 atoms are decreased, while the magnetic moments μ3 and μ4 for the interior M3 and M4 atoms are increased for each M13@(8, 8) hybrid system. In particular, different from the bulk FCC Fe that is antiferromagnetic, the minimum energy magnetic structure of FCC Fe13 free-standing nanowire is ferromagnetic. Furthermore, contrary to the cases of Co13 and Ni13 nanowires, the ferromagnetism is further enhanced after Fe13 nanowire is encapsulated inside (8, 8) silicon carbide nanotube.