Low Temperature Terahertz Nano-Imaging of BSCCO High Temperature Superconductor

Terahertz (THz) near-field imaging and nano-spectroscopy is a capable tool to research nano-scale low energy electromagnetic phenomena. Of particular interest are high-temperature superconductors (HTSC) whose characteristic energy scale exists in the THz regime. We discuss our recent development of a cryogenic, scanning near-field microscope suitable for nano-scale imaging and spectroscopy throughout the THz frequency range. We report THz near-field measurements of optimally doped and over-doped BSCCO-2212 thin film devices above and below their superconducting transition temperatures. Near-field can measure the c-axis Josephson plasma resonance (JPR) spectroscopically. Further, the large anisotropy between the in and out of plane plasma frequency caused by JPR also contributes to a hyperbolic polariton modes in the bulk of a thin film which can be detected by near-field imaging [1][2].
[1] H. T. Stinson et al, PRB 90, 014502 (2014)
[2] Dai, S., et al. Science 343.6175 (2014): 1125-1129.