Individual Fe-CNT Magnetometry P. Chris Hammel, Ohio State University, DMR 0807093

1. Individual Fe-CNT MagnetometryP. Chris Hammel, Ohio State University, DMR 0807093 • We have investigated the magnetization reversal in individual Fe-filled carbon nanotubes (Fe-CNT) using ultrasensitive cantilever magnetometry. • The magnetic moment of the Fe-CNT moment is detected by monitoring the oscillation frequency of the cantilever on which the nanotube is mounted • The reversal of the magnetization of an individual Fe-CNT is monitored as a function of magnetic field and temperature • Magnetization reversal occurs at the same field with variability of 0.02% of the switching field • We have developed a theoretical model fully describing magnetization reversal in an individual Fe-CNT (b) Cantilever frequency, (mHz) Magnetic field, (Gauss) a) Cantilever frequency in applied magnetic field. Magnetization reversal events can be seen. b) Individual Fe-CNT mounted on a cantilever Publication: “Magnetization reversal in an individual 25 nm iron-filled carbon nanotube”, P. Banerjee, F. Wolny, D. V. Pelekhov, M. R. Herman, K. C. Fong, U. Weissker, T. Mühl, Yu. Obukhov, A. Leonhardt, B. Büchner, and P. Chris Hammel, Appl. Phys. Lett.96, 252505 (2010) Schematic representation of magnetization reversal in Fe-CNT through thermal activation over a potential barrier as applied field is increased (from a1 to a4).

2. Individual Fe-CNT Magnetometry P. Chris Hammel, Ohio State University, DMR 0807093 • We have investigated magnetization switching in an individual Fe filled carbon nanotube (Fe-CNT) using a method of vibrating cantilever magnetometry. This research was performed in collaboration with IFW Dresden (Germany). • This research substantively involved three graduate research assistants, two postdoctoral researchers and one undergraduate student from OSU and two graduate students from Germany. This interaction included exchange visits by undergrads, grads and postdocs lasting from one to three months. • To provide needed background, the PI developed and taught a new course entitled “Experimental Magnetism“ during Winter quarter 2010. The course was popular with students from Physics, Chemistry, Materials Science and Biomedical Engineering and will be regularly taught in the future. • These nanowires are very promising as scanned nanomagnetic probes: they are high quality single crystal ferromagnetic nanowires that are environmentally protected by the enclosing carbon nanotube. They provide a highly localized field that can closely approximated as a magnetic monopole improving resolution and simplifying data interpretation