High spatial resolution charge sensing of quantum Hall states

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Electronics

Background:

• Charge distribution is key to understanding electronic system properties like dielectric response and charge ordering.
• Sensing charge distribution in 2D electronic systems under strong magnetic fields is challenging.

Purpose of the Study:

• To develop a novel, high-resolution technique for sensing charge distribution in 2D electronic systems.
• To apply this technique to study quantum Hall liquids in graphene and their response to impurities.

Main Methods:

• Utilized scanning tunneling microscopy to probe local chemical potential changes in a proximitized detector layer.
• Achieved high energy (<0.3 meV) and spatial (<10 nm) resolution, surpassing previous methods.

Main Results:

• Successfully mapped the chemical potential of quantum Hall liquids in graphene under high magnetic fields.
• Observed spatially oscillatory responses to charge impurities, consistent with the composite Fermi liquid model.
• Provided local probes of thermodynamic gaps in quantum Hall states.

Conclusions:

• The developed charge sensing technique offers unprecedented resolution for studying 2D electronic systems.
• This method enables detailed investigations of quantum Hall states, impurities, and novel electronic phenomena.
• Future applications include mapping moiré potentials, probing Wigner crystals, and investigating fractional charges.