Coherent emission from surface Josephson plasmons in striped cuprates.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36126100.
- Also identified by DOI 10.1073/pnas.2211670119 and PMC identifier 9522412.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The interplay between charge order and superconductivity remains one of the central themes of research in quantum materials. In the case of cuprates, the coupling between striped charge fluctuations and local electromagnetic fields is especially important, as it affects transport properties, coherence, and dimensionality of superconducting correlations. Here, we study the emission of coherent terahertz radiation in single-layer cuprates of the La<sub>2-x</sub>Ba<sub>x</sub>CuO<sub>4</sub> family, for which this effect is expected to be forbidden by symmetry. We find that emission vanishes for compounds in which the stripes are quasi-static but is activated when <i>c</i>-axis inversion symmetry is broken by incommensurate or fluctuating charge stripes, such as in La<sub>1.905</sub>Ba<sub>0.095</sub>CuO<sub>4</sub> and in La<sub>1.845</sub>Ba<sub>0.155</sub>CuO<sub>4</sub>. In this case, terahertz radiation is emitted by surface Josephson plasmons, which are generally dark modes, but couple to free space electromagnetic radiation because of the stripe modulation.