Research progress of ultrafast terahertz radiation in single-layer ferromagnets

Abstract:

Broadband terahertz radiation sources have an urgent practical application demand in terahertz science and technology, and are the core components for constructing terahertz application systems represented by spectroscopy and imaging. Compared with commonly used commercial terahertz sources, spin-optoelectronics-based terahertz radiation sources have a series of advantages such as ultra-wide frequency spectrum, solid-state stability, and low cost. Currently, the research on the theory, materials, and device technology of spin-optoelectronics-based terahertz radiation sources is still in its infancy. This paper mainly summarizes the terahertz generation mechanism of single-layer ferromagnetic layers in recent years, and the relationship between the polarity of terahertz radiation signals and the excitation configuration. By changing the direction of the magnetic field, the direction of the incident laser, and the direction of sample incidence, the contributions of ultrafast demagnetization, Anomalous Hall Effect(AHE), and Anomalous Nernst Effect(ANE) to the terahertz radiation characteristics can be effectively distinguished, providing a reference for the research in the field of terahertz spin-optoelectronics.