Coherent Emission from Surface Josephson Plasmons in Striped Cuprates

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${}_{2-x}$Ba${}_x$CuO${}_4$ 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 $c$-axis inversion symmetry is broken by incommensurate or fluctuating charge stripes, such as in La${}_{1.905}$Ba${}_{0.095}$CuO${}_4$ and in La${}_{1.845}$Ba${}_{0.155}$CuO${}_4$. 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.

25 pages, 9 figures

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Cited by in corpus (5)

• Time-linear quantum transport simulations with correlated nonequilibrium Green's functions
• Theory for Anomalous Terahertz Emission in Striped Cuprate Superconductors
• Accelerating analysis of Boltzmann equations using Gaussian mixture models: Application to quantum Bose-Fermi mixtures
• Optically-induced Umklapp shift currents in striped cuprates
• Enhanced coherent terahertz emission from critical superconducting fluctuations in YBa${}_2$Cu${}_3$O${}_{6.6}$