Cryogenic scanning photocurrent spectroscopy for materials responses to structured optical fields.

Area of Science:

• Quantum Materials Science
• Spectroscopy
• Optoelectronics

Background:

• Circular dichroism spectroscopy offers insights into quantum material degrees of freedom.
• The study of quantum materials' optoelectronic responses to structured light, especially at cryogenic temperatures, remains underexplored.

Purpose of the Study:

• To design and demonstrate a novel instrument for scanning spectroscopic photocurrent measurements.
• To investigate the optoelectronic responses of quantum materials to structured light with controlled spin and orbital angular momentum.

Main Methods:

• Integration of scanning spectroscopic photocurrent measurements with structured light.
• Utilizing a novel instrument for measurements on 2D materials and thin crystals.
• Performing measurements under magnetic fields (up to ±14 T) and cryogenic temperatures (down to 3 K).

Main Results:

• Spatially resolved photocurrent measurements with structured photons (500–700 nm).
• Demonstrated increasing photocurrents with increasing topological charge (|ℓ|).
• Revealed excitonic spectra, Zeeman splitting, and enhanced Landé g-factor in monolayer 2H-MoS2.

Conclusions:

• The developed instrument is versatile for investigating excitonic physics and optical selection rules.
• The study highlights the potential for exploring novel quantum materials and devices with structured light.
• The findings advance the understanding of quantum material responses to light with tailored angular momentum.