Local conductivity of metallic nano-materials by Electrodynamic Force Microscopy

In this work, a dual pass scanning probe microscopy, based on electric force microscopy (EFM), was employed to quantitatively investigate the local electrical conductivity of multi-walled carbon nanotubes (MWNTs). We show that EFM phase signal appears to be directly proportional to the local conductivity. To explain our results we propose a model that take into account the electrically charge tip apex that behaves as an oscillating current and thus generating a magnetic field. This dynamic magnetic field induces a Foucault current in metallic samples that undergo energetic looses by Joule effect. Our model, based on Electrodynamic Force Microscopy (EdFM), allows us to explain the negative phase inversion while scanning metallic materials.