Speaker
Description
Advances in THz generation have enabled a wide range of new scientific tools that probe previously inaccessible dynamics in materials. In the area of scanning tunneling microscopy the capability of generating large amplitude THz pulses have enabled practical ultrafast scanning tunneling microscopy experiments. In a THz-coupled scanning tunneling microscope (THz-STM), THz pulses couple to the tip of the microscope and provide a means to modulate the electric field at the microscope’s tunnel junction thus allowing ultrafast control of the tunnel current. Using a THz time domain spectrometer, THz pulses can then be used to achieve stroboscopic ultrafast time resolution in STM experiments. The operating principles of a THz-STM will be introduced along with the results of a recent experiment on charge density wave (CDW) state supported by niobium diselenide. In this experiment the response of the CDW state to strong electric field pulses was examined using a THz-STM to extract the response of individual atomic site. This allowed a measurement of the impact a single individual atomic defect has on the dynamic modes of the CDW state.
