Microwave Hall measurements using a circularly polarized dielectric cavity

Area of Science:

• Condensed Matter Physics
• Materials Science
• Electromagnetism

Background:

• Measuring microwave Hall conductivity in small metal crystals is challenging.
• Existing methods lack the sensitivity for detailed surface impedance tensor analysis.

Purpose of the Study:

• To develop a novel methodology for precise microwave Hall conductivity measurements.
• To extract all components of the surface impedance tensor in the skin-depth region.
• To enable exploration of topological quantum phenomena.

Main Methods:

• Development of a high-quality factor circularly polarized dielectric rutile (TiO2) cavity.
• Utilizing a hybrid coupler to generate circularly polarized microwaves.
• Application of the cavity perturbation technique and comparison of right- and left-handed circularly polarized modes.

Main Results:

• Successful measurement of microwave Hall conductivity in small Bi single crystals.
• Extraction of surface impedance tensor components under magnetic field.
• Confirmation of characteristic field dependence of the ac Hall angle consistent with DC measurements.

Conclusions:

• The developed technique offers significantly improved sensitivity for microwave Hall measurements.
• This method allows for accurate determination of surface impedance tensor components.
• Enables new avenues for exploring phenomena like time-reversal symmetry breaking.