Giant magnetoresistance of multiwall carbon nanotubes: modeling the tube/ferromagnetic-electrode burying contact

TL;DR

This study models the giant magnetoresistance in multiwall carbon nanotubes, highlighting how inter-wall interactions and electrode contact configurations influence the GMR sign and magnitude.

Contribution

It introduces a theoretical model analyzing the effects of inter-wall interactions and electrode coupling on GMR in multiwall carbon nanotubes, explaining inverse GMR phenomena.

Findings

Inverse GMR can occur with well-coupled walls and electrodes.

GMR sign depends on inter-wall interaction and nanotube length.

Inner nanotube contact status affects GMR behavior.

Abstract

We report on the giant magnetoresistance (GMR) of multiwall carbon nanotubes with ultra small diameters. In particular, we consider the effect of the inter-wall interactions and the lead/nanotube coupling. Comparative studies have been performed to show that in the case when all walls are well coupled to the electrodes, the so-called inverse GMR can appear. The tendency towards a negative GMR depends on the inter-wall interaction and on the nanotube le ngth. If, however, the inner nanotubes are out of contact with one of the electrodes, the GMR remains positive even for relatively strong inter-wall interactions regardless of the outer nanotube length. These results shed additional light on recently reported experimental data, where an inverse GMR was found in some multiwall carbon nanotube samples.