title: Giant enhancement and anomalous thermal hysteresis of saturation moment in magnetic nanoparticles embedded in multiwalled carbon nanotubes.
abstract: We report high-energy synchrotron X-ray diffraction spectrum and high-temperature magnetic data for multiwalled carbon nanotubes (MWCNTs) embedded with Fe and Fe3O4 nanoparticles. We unambiguously show that the saturation moments of the embedded Fe and Fe3O4 nanoparticles are enhanced by a factor of about 3.0 compared with what would be expected if they would be unembedded. More intriguingly the enhanced moments were completely lost when the sample was heated up to 1120 K, and the lost moments were completely recovered through two more thermal cycles below 1020 K. These novel results cannot be explained by the magnetism of the Fe and Fe3O4 impurity phases, the magnetic proximity effect between magnetic nanoparticles and carbon, and the ballistic transport of MWCNTs.
authors.affiliation: Department of Physics and Astronomy, California State University at Los Angeles, Los Angeles, California 90032, USA. gzhao2@calstatela.edu
authors.forename: Guo-meng
authors.initials: GM
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Ren
authors.forename: Pieder
authors.initials: P
authors.lastname: Beeli