Magnetoconductance of carbon nanotube p-n junctions

TL;DR

This paper investigates how magnetic fields influence the electrical conductance of carbon nanotube p-n junctions, revealing large, nonmonotonic magnetoconductance effects at low temperatures in both metallic and semiconducting tubes.

Contribution

It provides the first detailed analysis of magnetoconductance in carbon nanotube p-n junctions considering electron interactions and different tube types.

Findings

Low temperature magnetoconductance can be of order unity for long junctions.

Magnetoconductance is negative in metallic nanotubes.

Semiconducting nanotubes show nonmonotonic magnetoconductance, positive at small fields and negative at large fields.

Abstract

The magnetoconductance of p-n junctions formed in clean single wall carbon nanotubes is studied in the noninteracting electron approximation and perturbatively in electron-electron interaction, in the geometry where a magnetic field is along the tube axis. For long junctions the low temperature magnetoconductance is anomalously large: the relative change in the conductance becomes of order unity even when the flux through the tube is much smaller than the flux quantum. The magnetoconductance is negative for metallic tubes. For semiconducting and small gap tubes the magnetoconductance is nonmonotonic; positive at small and negative at large fields.