Terahertz Emission Functionality of High‐Temperature Superconductors and Similar Complex Systems

During the past two decades, terahertz (THz) science and technology have rapidly expanded in all fundamental and applied aspects of physical, chemical, and biological sciences. In physical sciences, these developments have been twofolds: i) the use of THz technology in understanding the complexities of materials and ii) the exploration of new THz functionalities of emerging materials for further advancement of THz technology. Here, the THz emission spectroscopy and the ultrafast functionality of three pillars of electronic and magnetic condensed matter systems that emerged in the following order: high‐temperature superconductors, colossal magnetoresistive manganites, and magnetoelectric multiferroics are reviewed. Emission functionality refers to the emitted THz radiation that carries the information of the underlying functional property of the material such that the overall effect evolves as the THz decoding of the information in a noninvasive manner and on an ultrafast timescale. Terahertz (THz) emission spectroscopy of three pillars of electronic and magnetic condensed matter systems, namely, the high‐temperature superconductors, colossal magnetoresistive manganites, and magnetoelectric multiferroics is comprehensively discussed here. Their ultrafast functionality has been explored in a way that the emitted THz radiation decodes the information of the underlying functional parameter of the system in a noninvasive manner and on an ultrafast timescale.