Surface magnetic states of Ni nanochains modified by using different organic surfactants.

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@Ni-SG nanochains with a spin glass (SG) surface layer, and Ni@Ni-NM 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 the saturation magnetization, usually observed with magnetic nanoparticles, is revealed to arise from the surface magnetic states with the present samples.