Quantum Hall effect in epitaxial graphene with permanent magnets

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• The quantum Hall effect (QHE) is a key phenomenon in condensed matter physics, typically observed in 2D electron systems under strong magnetic fields and low temperatures.
• Conventional QHE experiments often rely on expensive and complex superconducting magnets, limiting accessibility for research and education.

Purpose of the Study:

• To demonstrate the observation of the quantum Hall effect in epitaxial graphene using only permanent magnets.
• To explore the feasibility of a cost-effective experimental setup for studying QHE in graphene.

Main Methods:

• Epitaxial graphene grown on silicon carbide (SiC) was used as the 2D electron system.
• Commercial Neodymium-Iron-Boron (NdFeB) permanent magnets were employed to generate a sufficiently large and homogeneous magnetic field at low temperatures.
• A top gate was utilized to tune the electronic properties and control edge channel chirality.

Main Results:

• The quantum Hall effect was successfully observed in epitaxial graphene at Landau level filling factors of ±2, comparable to results obtained with superconducting magnets.
• The chirality of the QHE edge channels was demonstrated to be tunable via the top gate.
• The experiment confirmed the formation of well-developed quantum Hall states.

Conclusions:

• The use of permanent magnets provides a significantly more affordable and accessible method for observing the QHE in graphene.
• This breakthrough lowers the barrier for QHE research in graphene, paving the way for broader scientific investigation and potential technological applications.
• The findings highlight the potential of graphene-based systems for fundamental physics studies and device development.