Ultrafast dynamics evidence of strong coupling superconductivity in LaH10±δ
Yanling Wu, Xiaohui Yu, Jiazila Hasaien, Fang Hong, Pengfei Shan, Zhen‐Yu Tian, Yanan Zhai, Jiangping Hu, Jinguang Cheng, Jimin Zhao
Abstract
Recently, tremendous research interest has been aroused in clathrate superhydrides. However, their microscopic properties, especially the superconducting (SC) gap and electron-phonon coupling (EPC) strength, are largely unexplored experimentally. Here, we investigate the time-resolved ultrafast spectroscopy of a superconductor LaH10±δ under an ultrahigh pressure of 165 GPa. By analyzing the ultrafast dynamics of the quasiparticles, we experimentally obtain the SC gap Δ(0) = 53 ± 5 meV, revealing a gap ratio 2Δ(0)/kBTc = 5.6 and a gap parameter ϑ = 1.95. Significantly, we experimentally estimate $$\lambda \langle {\Omega }^{2}\rangle$$ = (2.4 ± 0.1) × 104 (meV)2, which corresponds to an EPC strength λ = 2.58 ± 0.11. These results together provide direct experimental evidence that strong EPC is responsible for the near-room-temperature superconductivity in clathrate superhydrides. Our investigation significantly advances the experimental exploration of superhydrides, and contributes to the ultrafast dynamics investigations of quantum materials under high pressures. Recently, clathrate superhydride superconductors have garnered significant attention. Here the authors measure the electron-phonon coupling strength and superconducting gap of an ultrahigh pressure superconductor LaH10±δ by ultrafast spectroscopy, revealing a strong coupling nature of the superconductivity.