Exploring the frontier of quantum materials through terahertz emission spectroscopy: a comprehensive review

Researchers at the University of Electronic Science and Technology of China, have published a review article on the terahertz (THz) radiation in quantum materials. The work, led by Surui Yang, Liang Cheng, and Jingbo Qi, offers a comprehensive exploration of the time-dependent photocurrents, shedding light on the up-to-date understanding of the physical processes involved.

The investigation, conducted at the forefront of ultrafast science, delves into the potential of THz radiation in unraveling the fundamental physics of quantum materials, with implications for the development of novel technologies. The review focuses on recent advancements in revealing the unique properties of quantum materials through THz emission spectroscopy.

I. Introduction: Decoding Terahertz Emission
Terahertz emission, the release of electromagnetic radiation within the THz range, has become a pivotal area of research due to its potential applications in diverse fields, including communications, sensing, imaging, and spectroscopy. The THz frequency range spans from 0.1 to 10 THz, offering a wavelength range of approximately 0.03 to 3 mm.
The study explores various mechanisms behind THz emission in materials, such as semiconductors, insulators, and conductors. The properties of THz emission depend on factors like electronic structure, carrier dynamics, magnetic moments, and device fabrication. Advancements in technology and the discovery of new materials with unique properties have expanded the possibilities in THz emission research. The review underscores the growing interest in THz emission and its potential applications across different disciplines.

II. Unraveling Quantum Materials through THz Emission
The review highlights the exploration of THz emission in quantum materials, focusing on those properties that defy classical physics. Under femtosecond pulsed-laser excitation, ultrafast photocurrent inducing THz emission is observed in materials exhibiting phenomena like topological nontrivial band structures, ferroelectricity, and superconductivity.
The interaction among charge carriers, lattice vibrations, and spin-related excitation is crucial in understanding THz emission from quantum materials. Studying THz emission aids in revealing underlying physical mechanisms, contributing to the development of new methods for manipulating quantum materials.

III. Focus on Topological Materials and Strongly Correlated Systems
The review delves into the recent developments of THz emission in two types of quantum materials: topological materials and strongly correlated systems. Specific emphasis is placed on topological insulators and semimetals (Dirac and Weyl) in topological materials, and multiferroics and superconductors in strongly correlated systems.
In conclusion, the researchers aim to inspire further exploration in this exciting and rapidly growing field. As theoretical interpretations of new experimental results continue to evolve, the review sets the stage for continued research into the intricate interplay between terahertz radiation and quantum materials.

For other inquiries, please contact:
Dr. Jingbo Qi
Email: jbqi@uestc.edu.cn
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China