Observation of Giant Orbital Magnetic Moments and Paramagnetic Shift in Artificial Relativistic Atoms and Molecules

TL;DR

This study uses scanning tunneling microscopy to create and analyze graphene quantum dots, revealing giant orbital magnetic moments and paramagnetic shifts, advancing understanding of relativistic quantum phenomena in artificial nanostructures.

Contribution

It demonstrates the creation and probing of artificial relativistic atoms and molecules in graphene QDs, revealing their unique magnetic responses and potential for magnetic sensing.

Findings

Giant orbital Zeeman splitting observed in single graphene QDs

Aharonov-Bohm oscillations detected in coupled QDs

Strong Van Vleck paramagnetic shift observed

Abstract

Massless Dirac fermions have been observed in various materials such as graphene and topological insulators in recent years, thus offering a solid-state platform to study relativistic quantum phenomena. Single quantum dots (QDs) and coupled QDs formed with massless Dirac fermions can be viewed as artificial relativistic atoms and molecules, respectively. Such structures offer a unique platform to study atomic and molecular physics in the ultra-relativistic regime. Here, we use a scanning tunneling microscope to create and probe single and coupled electrostatically defined graphene QDs to unravel the unique magnetic field responses of artificial relativistic nanostructures. Giant orbital Zeeman splitting and orbital magnetic moment are observed in single graphene QDs. While for coupled graphene QDs, Aharonov Bohm oscillations and strong Van Vleck paramagnetic shift are observed. Such properties of artificial relativistic atoms and molecules can be leveraged for novel magnetic field sensing modalities.