Giant Moment Enhancement of Magnetic Nanoparticles Embedded in Multi-Walled Carbon Nanotubes: Consistent with Ultrahigh Temperature Superconductivity

Abstract

We report high-temperature (300-1120 K) magnetization data of Fe and Fe 3 O 4 nanoparticles embedded in multi-walled carbon nanotubes. The magnetic impurity concerntations are precisely determined by both high-energy synchrotron x-ray diffractometer and inductively coupled plasma mass spectrometer. We unambiguously show that the magnetic moments of Fe and Fe 3 O 4 nanoparticles are enhanced by a factor of about 3 compared with what they would be expected to have for free (unembedded) magnetic nanoparticles. The magnetization enhancement factor is nearly independent of the applied magnetic field but depends significantly on the cooling rate. What is