Modified Martin-Puplett interferometer for magneto-optical Kerr effect measurements at sub-THz frequencies

Area of Science:

• Condensed Matter Physics
• Spectroscopy
• Quantum Materials

Background:

• The magneto-optical Kerr effect (MOKE) is crucial for studying magnetic properties of materials.
• Existing MOKE spectroscopy methods often require complex setups and reference measurements.
• Characterizing quantum materials at extreme conditions (low temperatures, high magnetic fields) demands advanced spectroscopic tools.

Purpose of the Study:

• To develop and demonstrate a novel magneto-optical Kerr effect (MOKE) spectrometer.
• To enable simultaneous measurement of MOKE response functions (Kerr rotation and ellipticity) with high accuracy.
• To facilitate the study of quantum materials under extreme conditions.

Main Methods:

• Utilized a modified Martin-Puplett interferometer.
• Employed continuous wave sub-terahertz (sub-THz) low-power radiation over a broad frequency range.
• Integrated the spectrometer with a cryostat for variable temperature and magnetic field studies.

Main Results:

• Achieved simultaneous measurement of frequency-dependent MOKE response (Kerr rotation and ellipticity).
• Demonstrated sub-milliradian accuracy without the need for reference measurements.
• Successfully tested the spectrometer's functionality using an undoped Indium Antimonide (InSb) wafer.

Conclusions:

• The developed MOKE spectrometer is a versatile tool for probing quantum materials.
• Enables advanced studies of unconventional superconductors, 2D electron gases, and quantum magnets.
• Provides a new capability for investigating optical Hall response in materials at sub-Kelvin temperatures and high magnetic fields.