Theory for Anomalous Terahertz Emission in Striped Cuprate Superconductors

Abstract

Recent experiments in the doped cuprates La${}_{2-x}$Ba${}_x$CuO${}_4$ have revealed the emission of anomalous terahertz radiation after impulsive optical excitation. Here, we theoretically investigate the nonlinear electrodynamics of such striped superconductors and explore the origin of the observed radiation. We argue that photoexcitation is converted into a photocurrent by a second-order optical nonlinearity, which is activated by the breaking of inversion symmetry in certain stripe configurations. We point out the importance of including Umklapp photocurrents modulated at the stripe periodicity itself, which impulsively drive surface Josephson plasmons and lead to a resonant structure of outgoing radiation, consistent with the experiments. We speculate on the utility of the proposed mechanism in the context of generating tunable terahertz radiation.

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Cited by in corpus (3)

• 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${}_{6.6}$