Magnetic field asymmetry of nonlinear transport in carbon nanotubes

TL;DR

This paper investigates magnetic field asymmetry in nonlinear electron transport through carbon nanotubes, revealing temperature-dependent behaviors and unexplained magnetoresistance, advancing understanding of nanoscale quantum effects.

Contribution

It provides the first measurement of B-asymmetric nonlinear transport terms in carbon nanotubes and links these to electron interactions and nanotube chirality.

Findings

B-asymmetric terms are small at high temperatures

Low-temperature fluctuations indicate mesoscopic effects

Significant unexplained magnetoresistance observed

Abstract

We demonstrate that nonlinear transport through a two-terminal nanoscale sample is not symmetric in magnetic field B. More specifically, we have measured the lowest order B-asymmetric terms in single-walled carbon nanotubes. Theoretically, the size of these terms can be used to infer both the strength of electron-electron interactions and the handedness of the nanotube. Consistent with theory, we find that at high temperatures the B-linear term is small and has a constant sign independent of Fermi energy, while at low temperatures it develops mesoscopic fluctuations. We also find significant magnetoresistance of nanotubes in the metallic regime which is unexplained.