Lightwave-driven terahertz microscopy of emergent phenomena in two-dimensional materials
Abstract
Ultrafast lightwave-driven terahertz scanning tunneling microscopy (THz-STM) will be used to study and control emergent phenomena in low-dimensional materials with simultaneous atomic spatial resolution and femtosecond temporal resolution. One focused thrust is the exploration of atomic scale ultrafast dynamics in ultrathin topological materials (e.g., WTe2) and ultrathin charge density wave materials (TiSe2, VSe2, VTe2, TaS2). We will examine the effects of layer thickness, lateral size, defects, dopants, phases, and heterostructured stacking on the ultrafast evolution of these materials following optical and THz excitation, all with atomic spatial resolution. Another focus is to study THz field-induced physical changes manifested at the STM tip-surface junction, including electric-field-driven band gap tuning in 2D material heterostructures. THz pulses will also be used for nanofabrication, with self-assembled single-atom-wide nanowires as the main target. This project is a collaboration that brings together state-of-the-art experimental capabilities from the US and Taiwan. The US partner group will perform ultrafast THz-STM experiments in a fully functional, low-temperature, ultrahigh vacuum THz-STM system. The Taiwan partner will grow, characterize, and transport transition metal dichalcogenide thin films made by molecular beam epitaxy (MBE), leveraging their established capabilities in this area. The project builds on an existing collaboration between the groups, which has recently discovered THz-driven nanofabrication. This intriguing prospect for device fabrication will be developed through the current project. The project will also use recent THz-STM measurements on bulk WTe2 as a springboard to explore atomic scale THz characterization and control of quantum materials in reduced dimensions. Combining the unique spatio-temporal regime accessible by THz-STM with versatile-sophisticated sample preparation-characterization ensures a highly synergistic collaboration. This project will deepen understanding of how to control quantum material properties - such as topological phases and collective states in reduced dimensions - on extreme spatio-temporal scales.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 05, 2025
- Source ID
- FA23862414042
Entities
People
- Tyler L. Cocker
Organizations
- Air Force Office of Scientific Research
- Michigan State University
- United States Air Force