Transport across a carbon nanotube quantum dot contacted with ferromagnetic leads: Experiment and nonperturbative modeling

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.

Impact of Tunnel-Barrier Strength on Magnetoresistance in Carbon Nanotubes

“…In the former case, huge variations of the MR effect between −80% and +120% have been observed [10][11][12][13]. These occur owing to changes of the position and the width of the Coulomb resonances, which, in turn, depend on the magnetic configuration (parallel or antiparallel) of the magnetic moments of the contacts, and oscillate with gate and bias voltage [13]. The oscillating behavior with gate and bias voltage has also been found in the strong coupling regime [14,15], though with a significantly reduced MR amplitude not exceeding 9%.…”

“…The two limiting cases are the quantum * carola.meyer@uos.de dot regime, when the coupling is weak, and the Fabry-Pérot regime for strong coupling leading to high transmission [9]. In the former case, huge variations of the MR effect between −80% and +120% have been observed [10][11][12][13]. These occur owing to changes of the position and the width of the Coulomb resonances, which, in turn, depend on the magnetic configuration (parallel or antiparallel) of the magnetic moments of the contacts, and oscillate with gate and bias voltage [13].…”

Towards Noise Simulation in Interacting Nonequilibrium Systems Strongly Coupled to Baths

“…The QME formulated in the basis of system many-body states (thus accounting for intra-system interactions) has difficulty treating strong system-bath couplings. In this respect, an important extension of the latter approach is formulation of the real time perturbation theory (and similar approaches) 44 – 50 , which allowed evaluation of shot noise accounting for system-bath coupling within a systematic perturbation expansion 51 .…”

The Electronic Structure of Short Carbon Nanotubes: The Effects of Correlation

“…A similar approach was already applied to closed polyacenes structures [13] whereas most of previous works on nanotubes [14][15][16][17][18][19][20][21][22] or nanoribbons [23] principally rely on density functional theory or tight binding results. The main conclusion of studies on There also have been some studies in the solid-state community on the energy spectrum [24] and properties of single walled nanotubes [25] using sophisticated analytic tools. Similar structures as those considered consist in an antiferromagnetic coupling of two electrons localized in the edge orbitals.…”