Optical and magnetic measurements of gyroscopically stabilized graphene nanoplatelets levitated in an ion trap

TL;DR

This study demonstrates frequency locking and stabilization of levitated graphene nanoplatelets in an ion trap, enabling nanoscale material measurements through optical and magnetic techniques.

Contribution

It introduces a method to control and analyze the rotation of levitated graphene nanoplatelets, revealing their magnetic and diamagnetic properties with high precision.

Findings

Frequency locking stabilizes nanoplatelet orientation.

Residual rotation dynamics are influenced by magnetic fields.

Measured magnetic and diamagnetic properties match theoretical predictions.

Abstract

Using optical measurements, we demonstrate that the rotation of micron-scale graphene nanoplatelets levitated in a quadrupole ion trap in high vacuum can be frequency locked to an applied radio frequency (rf) electric field. Over time, frequency locking stabilizes the nanoplatelet so that its axis of rotation is normal to the nanoplatelet and perpendicular to the rf electric field. We observe that residual slow dynamics of the direction of the axis of rotation in the plane normal to the rf electric field are determined by an applied magnetic field. We present a simple model that accurately describes our observations. From our data and model we can infer both a diamagnetic polarizability and a magnetic moment proportional to the frequency of rotation, which we compare to theoretical values. Our results establish that trapping technologies have applications for materials measurements at the nanoscale.