Low Temperature Terahertz Nano Imaging of WTe2 Thin Film

We discuss the development of cryogenic scanning near-field microscope suitable for nano-scale imaging and spectroscopy at terahertz frequency range with the spatial resolution below 130 nm[1]. We report terahertz near-field measurement of WTe2 thin film of 1 to 3 layers[2] above and below the metal-insulator transition. Clear contrast in near-field signal can be observed among regions with different layer numbers and between metallic and insulating state.
[1] Stinson, H. T., et al. "Infrared nanospectroscopy and imaging of collective superfluid excitations in anisotropic superconductors." Physical Review B 90.1 (2014): 014502.
[2] Fei, Zaiyao, et al. "Edge conduction in monolayer WTe 2." Nature Physics 13.7 (2017): 677.