Helicity-Sensitive Terahertz Detection in Monolayer 1T'-WTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Information Science

Background:

• Valleytronics leverages electronic properties of energy band extrema in momentum space.
• Two-dimensional transition metal dichalcogenides (TMDCs) enable valley information control via light's spin angular momentum.
• Previous studies were limited to visible/near-infrared light, restricting TMDC carrier excitation.

Purpose of the Study:

• To explore valleytronics in monolayer 1T eal-WTe2 using terahertz (THz) light.
• To investigate the photogalvanic effect (PGE) for valley manipulation.
• To demonstrate control over photocurrent using circular polarization and electric fields.

Main Methods:

• Utilized a circularly polarized THz laser to selectively excite valleys in monolayer 1T eal-WTe2.
• Measured helicity-dependent photoresponse.
• Analyzed photocurrent control by circular polarization and external electric fields.

Main Results:

• Demonstrated a helicity-dependent photoresponse in monolayer 1T eal-WTe2 via the photogalvanic effect (PGE).
• Showcased photocurrent control through circular polarization and external electric fields.
• Observed tunable bandgap in WTe2 due to tunable Berry curvature dipole.

Conclusions:

• Monolayer 1T eal-WTe2 is a promising platform for long-wavelength photonic properties and valleytronics.
• The study provides a versatile method for controlling and detecting valleytronics.
• Potential applications include on-chip THz imaging and quantum information processing.