Subcycle Transient Scanning Tunneling Spectroscopy with Visualization of Enhanced Terahertz Near Field Shoji Yoshida Hideki Hirori Takehiro Tachizaki Katsumasa Yoshioka Yusuke Arashida Zi-Han Wang Yasuyuki Sanari Osamu Takeuchi Yoshihiko Kanemitsu Hidemi Shigekawa 10.1021/acsphotonics.9b00266.s001 https://acs.figshare.com/articles/journal_contribution/Subcycle_Transient_Scanning_Tunneling_Spectroscopy_with_Visualization_of_Enhanced_Terahertz_Near_Field/8159090 The recent development of optical technology has enabled the practical use of a carrier-envelope phase-controlled monocycle electric field in the terahertz (THz) regime. By combining this technique with metal nanostructures such as nanotips, which induce near-field enhancement, the development of novel applications is anticipated. In particular, THz scanning tunneling microscopy (THz-STM) is a promising technique for probing ultrafast dynamics with the spatial resolution of STM. However, the modulation of the THz waveform is generally accompanied by an enhancement of the electric field, which is unknown in actual measurement environments. Here, we present a method enabling direct evaluation of the enhanced near field in the tunnel junction in THz-STM in the femtosecond range, which is essential for the use of the THz near field. In the tunneling regime, it was also demonstrated that the transient electronic state excited by an optical pulse can be evaluated using the THz-STM, and the ultrafast carrier dynamics in 2H-MoTe<sub>2</sub> excited by an optical pulse was reproducibly probed. 2019-05-16 00:00:00 Enhanced Terahertz femtosecond range carrier-envelope phase-controlled monocycle 2 H-MoTe 2 metal nanostructures pulse Subcycle Transient Scanning Tunneling Spectroscopy THz scanning tunneling microscopy measurement environments ultrafast dynamics tunnel junction technique near-field enhancement STM ultrafast carrier dynamics THz waveform tunneling regime novel applications THz-STM