Orbital magnetic moments in pure and doped carbon nanotubes

TL;DR

This paper investigates the orbital magnetic moments in pure and doped carbon nanotubes, revealing their dependence on conducting properties, length, temperature, and doping, with implications for their magnetic behavior and electron-hole symmetry.

Contribution

It provides a detailed analysis of how orbital magnetic moments in carbon nanotubes depend on their electronic properties, doping, and temperature, highlighting unique and novel dependencies.

Findings

Orbital magnetic moments depend on conducting properties, length, and temperature.

Doped nanotubes show strong dependence on radius and chirality.

Temperature can switch nanotubes from diamagnetic to paramagnetic.

Abstract

The unusual band structure of carbon nanotubes (CNs) results in their remarkable magnetic properties. The application of magnetic field parallel to the tube axis can change the conducting properties of the CN from metallic to semiconducting and vice versa. Apart from that B induces (via the Bohm-Aharonov effect) orbital magnetic moments $\mu_{orb}$ in the nanotube. These moments are studied both in pure and hole- or electron-doped CNs, isolated or in a circuit. Remarkably, $\mu_{orb}$ in pure CNs depends uniquely on their original conducting properties, length, and temperature, but it does not depend on the nanotube radius or the particular chirality. In doped nanotubes the magnetic moments can be strongly altered and depend on the radius and chirality.Temperature can even change their character from diamagnetic at low T to paramagnetic at high T. A full electron-hole symmetry in doped tubes is also revealed.