Surface Josephson plasma waves in a high-temperature superconductor
| Autor: | Lu, Q., Bollinger, A. T., He, X., Sundling, R., Bozovic, I., Gozar, A. |
|---|---|
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | NPJ | Quantum Materials 5, 69 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/s41535-020-00272-8 |
| Popis: | Electron density oscillations with acoustic dispersions and sustained at boundaries between different media provide information about surface and interface properties of hetero-structures. In ultra-thin metallic films these plasmonic excitations are heavily damped. Superconductivity is predicted to reduce dissipation allowing detection of these resonances. Emerging low-loss interface Cooper-pair waves have been studied before, however, the observation of surface-confined Josephson plasmons has remained elusive. Here, we report on generation and coupling to these excitations in an ultrathin single-crystal film of high-temperature superconductor La1.85Sr0.15CuO4. The film becomes brighter than Au below the critical temperature when probed with sub-gap THz photons. We show that the enhanced signal in the superconducting state, which can be visualized with a spatial resolution better than {\lambda}/3,000, originates from near-field coupling of light to surface Josephson plasmons. Our results open a path towards non-invasive investigation of enhanced superconductivity in artificial multilayers, buried interface states in topological hetero-structures, and non-linear phenomena in Josephson devices. Comment: references added; expanded discussion; journal reference |
| Databáze: | arXiv |
| Externí odkaz: |
|