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Detection of Nanoscale Magnetic Activity Using a Single Carbon

Summary: Detection of Nanoscale Magnetic
Activity Using a Single Carbon
Caterina Soldano,*,,| Swastik Kar,*,,| Saikat Talapatra,§
Saroj Nayak, and Pulickel M. Ajayan
Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic
Institute, Troy, New York 12180, Department of Mechanical Engineering and
Materials Science, Rice UniVersity, Houston, Texas 77006, and Department of Physics,
Southern Illinois UniVersity Carbondale, Carbondale, Illinois 62901
Received August 12, 2008; Revised Manuscript Received October 6, 2008
The ultimate conductometric sensor for ferromagnetic activity of nanoscale magnetic materials could be a single carbon nanotube. We show
that the electrical conductance of an individual carbon nanotube is sensitive to magnetic transitions of nanoscale magnets embedded inside
it. To establish this, multiwall carbon nanotubes were impregnated with cobalt nanoclusters. Temperature dependence of conductance (5 K
< T < 300 K) of these nanotubes shows the usual Lušttinger-liquid power law behavior at higher temperatures and an onset of Coulomb
blockade at lower temperatures. At the lowest temperature (T 6 K), the differential conductance (dI/dV versus V) develops aperiodic fluctuations
under an external magnetic field B, the rms amplitude of which grows with the magnitude of the field itself. Low-temperature magnetoconductance,
studied as function of temperature and bias, can be interpreted in terms of weak antilocalization effects due to the presence of the magnetized
clusters. The temperature dependence of magnetoconductance further presents a "peak"-like feature and slow dynamics around T ) 55 K,
which depend on the magnitude and history of the applied B field. These observations indicate a sensitivity of electronic transport in the


Source: Ajayan, Pulickel M. - Department of Mechanical Engineering and Materials Science, Rice University


Collections: Materials Science