Linear and non-linear THz response of NIR-driven YBCO

We investigated the NIR-light driven transient response in the underdoped cuprate superconductor YBa2Cu3Oy (YBCO) using linear and non-linear THz probes to trace for fingerprints of light induced coherence. One prominent fingerprint is the light induced emergence of 1/ω-like spectral behavior in the imaginary part of the optical conductivity. However, the THz third-harmonic generation arising from the ac-driven Josephson current along the c-axis is absent under NIR photoexcitation. That shows that the NIR light induced state is distinct from the long-range-ordered SC state in equilibrium.

Kota Katsumi, Morihiko Nishida, Stefan Kaiser, Shigeki Miyasaka, Setsuko Tajima, and Ryo Shimano

Phys. Rev. B 107, 214506 (2023)