Transport across a carbon nanotube quantum dot contacted with ferromagnetic leads: experiment and non-perturbative modeling

TL;DR

This study investigates tunneling magneto-resistance in carbon nanotube quantum dots with ferromagnetic contacts, revealing gate-dependent variations and a double-dip signature, supported by non-perturbative theoretical modeling.

Contribution

The paper combines experimental measurements with non-perturbative DSO modeling to explain TMR variations in nanotube quantum dots with ferromagnetic leads, a novel approach in this context.

Findings

TMR varies strongly with gate voltage.

A double-dip TMR signature is observed.

The DSO model qualitatively reproduces experimental data.

Abstract

We present measurements of tunneling magneto-resistance (TMR) in single-wall carbon nanotubes attached to ferromagnetic contacts in the Coulomb blockade regime. Strong variations of the TMR with gate voltage over a range of four conductance resonances, including a peculiar double-dip signature, are observed. The data is compared to calculations in the "dressed second order" (DSO) framework. In this non-perturbative theory, conductance peak positions and linewidths are affected by charge fluctuations incorporating the properties of the carbon nanotube quantum dot and the ferromagnetic leads. The theory is able to qualitatively reproduce the experimental data.