Shape-sensitive Pauli blockade in a bent carbon nanotube

TL;DR

This paper models the Pauli blockade in a bent carbon nanotube double quantum dot, revealing how tube shape and g-factor anisotropy influence leakage current, enabling mechanical control and shape characterization.

Contribution

It introduces a model incorporating g-factor anisotropy and tube shape effects, explaining experimental results and predicting shape-sensitive leakage current behavior.

Findings

Leakage current exhibits magnetic anisotropy linked to nanotube orientation.

Leakage current is highly sensitive to nanotube shape in certain parameters.

Mechanical manipulation can control electron transport via tube shape.

Abstract

Motivated by a recent experiment [F. Pei et al., Nat. Nanotech. 7, 630 (2012)], we theoretically study the Pauli blockade transport effect in a double quantum dot embedded in a bent carbon nanotube. We establish a model for Pauli blockade, taking into account the strong g-factor anisotropy that is linked to the local orientation of the nanotube axis in each quantum dot. We provide a set of conditions under which our model is approximately mapped to the spin-blockade model of Jouravlev and Nazarov [O. N. Jouravlev and Y. V. Nazarov, Phys. Rev. Lett. 96, 176804 (2006)]. The results we obtain for the magnetic anisotropy of the leakage current, together with their qualitative geometrical explanation, provide a possible interpretation of previously unexplained experimental results. Furthermore, we find that in a certain parameter range, the leakage current becomes highly sensitive to the shape of the tube, and this sensitivity increases with increasing g-factor anisotropy. This mutual dependence of the electron transport and the tube shape allows for mechanical control of the leakage current, and for characterization of the tube shape via measuring the leakage current.