Nonlinear magnetotransport in interacting chiral nanotubes

Magnetoconductance of carbon nanotube p-n junctions

The magnetoconductance of p-n junctions formed in clean single wall carbon nanotubes is studied 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. The identified magnetoconductance mechanism is relevant to magnetotransport in undoped metallic and small gap tubes in the presence of a long range disorder potential.

Spin-orbit-induced spin-density wave in a quantum wire

We present analysis of the interacting quantum wire problem in the presence of magnetic field and spin-orbit interaction. We show that an interesting interplay of Zeeman and spin-orbit terms, facilitated by the electron-electron interaction, results in the spin-density wave state when the magnetic field and spin-orbit axes are orthogonal. This strongly affects charge transport through the wire: With the spin-density wave stabilized, single-particle backscattering off a nonmagnetic impurity becomes irrelevant. The sensitivity of the effect to the direction of the magnetic field can be used for experimental verification of this proposal.