Electronic Transport Spectroscopy of Carbon Nanotubes in a Magnetic Field

TL;DR

This study uses magnetic field spectroscopy to explore the energy level structure and magnetic moments of carbon nanotube quantum dots, revealing orbital splitting, spin-orbital interactions, and anticrossing behavior.

Contribution

It provides detailed insights into the spin and orbital contributions to magnetic moments in carbon nanotube quantum dots using inelastic cotunneling spectroscopy.

Findings

Large orbital splitting induced by magnetic field

Opposite magnetic moments of orbital states demonstrated

Anticrossing behavior observed at zero magnetic field

Abstract

We report magnetic field spectroscopy measurements in carbon nanotube quantum dots exhibiting four-fold shell structure in the energy level spectrum. The magnetic field induces a large splitting between the two orbital states of each shell, demonstrating their opposite magnetic moment and determining transitions in the spin and orbital configuration of the quantum dot ground state. We use inelastic cotunneling spectroscopy to accurately resolve the spin and orbital contributions to the magnetic moment. A small coupling is found between orbitals with opposite magnetic moment leading to anticrossing behavior at zero field.