Volume 237, 2022

Signatures of collective modes in fifth harmonic generation of BCS superconductor

Abstract

Recent advances in the field of THz spectroscopy allow for controlled experiments to measure signatures of collective excitations in the conventional s-wave superconductor in the fifth harmonic generation current (FHG). Here, we analyze this process theoretically within the Anderson pseudospin formalism and use a periodic multicycle pulse setup, where the driving electromagnetic field points in the direction of a lattice vector. We investigate the interplay of the Higgs mode contribution to the fifth harmonic generation current and compare it to other contributing mechanisms, such as charge density fluctuations (CDF). Similar to the third harmonic generating current we show that the signal in the FHG is also dominated by the CDF. Most importantly, we predict a double peak signature in the frequency dependence of the intensity amplitude of the FHG current with one peak located at Ω = Δ0 (4Ω = 4Δ0) and another one at Ω = Δ0/2 (4Ω = 2Δ0). The resonant enhancement in the latter case is indicative of the higher order coupling to the Higgs mode or CDF, while the former is reminiscent of the THG describing the coupling of CDF and the Higgs mode with 2 single photons.

Graphical abstract: Signatures of collective modes in fifth harmonic generation of BCS superconductor

Associated articles

Article information

Article type
Paper
Submitted
22 mar 2022
Accepted
11 apr 2022
First published
11 apr 2022

Faraday Discuss., 2022,237, 186-197

Signatures of collective modes in fifth harmonic generation of BCS superconductor

P. Derendorf, M. A. Müller and I. M. Eremin, Faraday Discuss., 2022, 237, 186 DOI: 10.1039/D2FD00067A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements