  Three powder samples of Ni nanochains formed of polycrystalline Ni
nanoparticles with an estimated diameter of about 30 nm have been synthesized
by a wet chemical method using different organic surfactants. These samples,
having magnetically/structurally core-shell structures, all with a
ferromagnetic Ni core, are Ni@Ni3C nanochains, Ni@NiSG nanochains with a spin
glass (SG) surface layer, and Ni@NiNM nanochains with a nonmagnetic (NM)
surface layer. The average thickness of the shell for these three samples is
determined as about 2 nm. Magnetic properties tailored by the different surface
magnetism are studied. In particular, suppression in saturation magnetization
usually observed with magnetic nanoparticles is revealed to arise from the
surface magnetic states with the present samples.
