Giant magnetic moment enhancement of nickel nanoparticles embedded in multiwalled carbon nanotubes

Abstract

We report a giant magnetic moment enhancement of ferromagnetic nickel nanoparticles (11 nm) embedded in multiwalled carbon nanotubes (MWCNTs). High-energy synchrotron x-ray diffraction experiment and chemical analysis are used to accurately determine the ferromagnetic nickel concentration. Magnetic measurements show that the room-temperature saturation magnetization of the nickel nanoparticles embedded in the MWCNTs is enhanced by a factor of about $3.4\ifmmode\pm\else\textpm\fi{}1.0$ as compared with what they would be expected to have for free nanoparticles. The giant moment enhancement is unlikely to be explained by a magnetic proximity effect but possibly arise from the interplay between ferromagnetism in nickel nanoparticles and strong diamagnetism in multiwalled carbon nanotubes.