Exploring the magnetically induced field effect in carbon nanotube-based devices

We report on the high magnetic field study of transport properties of gated small diameter (quasi)-metallic single wall carbon nanotubes (CNTs). We show that initially metallic CNT devices operate as CNT field-effect transistors under strong magnetic fields. This effect results from the Aharonov-Bohm phenomena at the origin of a band gap opening in metallic nanotubes. Strong exponential magnetoresistance observed up to room temperature is the ultimate consequence of the linear increase of the band gap with a magnetic field. Finally, we show that intrinsic characteristics of a quasi-metallic CNT, such as the helical symmetry, as well as the parameters of the Schottky barriers formed at the contacts, can be deduced from temperature-dependent magnetoconductance measurements.