Quantum-Geometry-Enabled Terahertz Rectification in the Weyl Semimetal TaP.

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Terahertz Photonics

Background:

• Noncentrosymmetric crystals rectify light via Berry-curvature dipole (BCD) for direct current (DC) generation, especially with terahertz (THz) photons.
• Topological Weyl semimetals (WSMs) offer ideal platforms due to large Berry curvature and broken inversion symmetry, but experimental BCD-driven THz photoresponse is challenging.

Purpose of the Study:

• To experimentally demonstrate room-temperature, junction-free THz current rectification in a Weyl semimetal.
• To confirm the photoresponse is explicitly driven by the intrinsic Berry curvature dipole.
• To explore the potential of WSMs for high-performance THz devices.

Main Methods:

• Utilized type-I Weyl semimetal tantalum phosphide (TaP) for THz current rectification experiments.
• Applied transverse THz polarization to generate longitudinal photocurrents.
• Characterized response time, bandwidth, and device performance as a heterodyne mixer.

Main Results:

• Achieved room-temperature, junction-free THz current rectification in TaP, driven by its intrinsic BCD.
• Observed longitudinal photocurrents from transverse THz polarization with a 0.96 μs response time across a 0.04-0.53 THz bandwidth.
• Demonstrated a 25 dB conversion gain as a room-temperature heterodyne mixer with a 20 GHz intermediate-frequency (IF) bandwidth.

Conclusions:

• Established TaP Weyl semimetals as a viable platform for topological optoelectronics.
• Confirmed the direct link between Berry curvature dipole and THz photoresponse, highlighting quantum geometric effects.
• Paved the way for developing high-performance THz devices for applications like 6G wireless communication.