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TitleMagnetic properties of multiwalled carbon nanotubes as a function of acid treatment
Publication TypeJournal Article
Year of Publication2006
AuthorsEllis, A.V., and Ingham B.
JournalJournal of Magnetism and Magnetic Materials
Pagination378 - 381
Date Published2006
ISSN03048853 (ISSN)
KeywordsAcid treatment, Carbon nanotubes, Fe nanoparticles, Fermi level, Magnetic properties, Magnetic susceptibility, Magnetization, Magnetometers, Paramagnetic contribution, SQUIDs
AbstractWe investigate the electronic properties of multiwalled carbon nanotubes both before and after acid treatment with concentrated sulphuric and nitric acids. Magnetic susceptibility measurements were performed using a SQUID magnetometer and show that there is a considerable enhancement in the density of states at the Fermi level. The data shows that the diamagnetic influence from the graphitic nanotubes dominates. We experimentally observe, after acid treatment, that the diamagnetic susceptibility remains unchanged at 5 K but notably decreases at 77 K. We propose the acid treatment has increased the Van Vleck paramagnetic contribution lowering the diamagnetic response from the π-electron orbital magnetisation. The Van Vleck paramagnetic contribution is finite-temperature dependent with a diminishing contribution at higher fields. © 2005 Elsevier B.V. All rights reserved.

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