Strong Metasurface–Josephson Plasma Resonance Coupling in Superconducting La2−xSrxCuO4. Issue 21 (21st August 2019)

• Record Type: Journal Article
• Authors: Schalch, Jacob S.; Post, Kirk; Duan, Guangwu; Zhao, Xiaoguang; Kim, Young Duck; Hone, James; Fogler, Michael M.; Zhang, Xin; Basov, Dmitri N.; Averitt, Richard D.
• Is Part Of: Advanced optical materials. Volume 7:Issue 21(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-08-21
• Subjects: Josephson plasmonics -- metamaterials -- superconductivity -- THz -- ultrastrong coupling; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.201900712
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: Terahertz spectroscopy of the c ‐axis Josephson plasma resonance (JPR) in high‐temperature cuprates is a powerful probe of superconductivity, providing a route to couple to and interact with the condensate. Electromagnetic coupling between metasurface arrays of split ring resonators (SRRs) and the JPR of a La2− x Sr x CuO4 single crystal ( T c = 32 K) is investigated. The metasurface resonance frequency (ωMM ), determined by the SRR geometry, is swept through the JPR frequency (ωJPR = 1.53 THz) using a series of interchangeable tapes applied to the same single crystal. Terahertz reflectivity measurements on the resulting hybrid superconducting metamaterials (HSMMs) reveal anticrossing behavior characteristic of strong coupling. The experimental results, validated with numerical simulations, indicate a normalized Rabi frequency of ΩR = 0.29. Further, it is shown that HSMMs with ωMM > ωJPR provide a route to couple to hyperbolic waveguide modes in c ‐axis cuprate samples. This work informs future possibilities for optimizing the coupling strength of HSMMs and investigating nonlinear superconductivity under high field terahertz excitation. Abstract : High‐temperature superconductors are amenable to electromagnetic control through manipulation of Josephson interlayer phase coherence using Terahertz fields. This possibility is investigated using reusable ultrathin metasurface "tapes" consisting of gold split ring resonators adhered a c ‐axis oriented single crystal of superconducting La2− x Sr x CuO4 . Terahertz reflectivity measurements of the resulting hybrid superconducting metamaterials reveal anticrossing behavior indicative of strong coupling.