Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Superconductivity: Poster Session

TT 30.26: Poster

Thursday, September 8, 2022, 15:00–18:00, P1

Fifth harmonic generated currents in conventional s-wave superconductor — •Pascal Derendorf and Ilya Eremin — Institut für Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany

Recent advances in the field of THz spectroscopy allow for controlled experiments to measure the Higgs modes signature in the Fifth Harmonic Generation (FHG), which was first measured by Z. X. Wang et al [1]. Here, we analyze a periodic multicycle pulse setup, where the driving electromagnetic field solely points into the direction of a lattice vector. We investigate the role of the Higgs mode in the clean-limit FHG of a s-wave superconductor and compare it to other contributing mechanisms, such as charge density fluctuations (CDF) and the phase mode. Further, we show that the signal in the FHG is dominated by the CDF, similar to the third harmonic generated currents. We predict a double peak signature in the frequency resolved intensity amplitude of the FHG for all three mechanisms with one peak being located at 2Ω=2Δ and the other one at 2Ω=Δ. The resonant enhancement at 2Ω=Δ is indicative of the next higher order coupling to the Higgs mode implying that it carries 4Ω. The other resonance at 2Ω=2Δ is reminiscent of the Third Harmonic Generation and could therefore describe e.g. the Higgs mode interacting with 3 single photons.

[1] Z. X. Wang et al., arXiv: 2107.07488