Baldini, Edoardo Mann, Andreas Mallett, Benjamin P. P. Arrell, Christopher Mourik, Frank van Wolf, Thomas Mihailovic, Dragan Tallon, Jeffrey L. Bernhard, Christian Lorenzana, José Carbone, Fabrizio 2017-01-03 In cuprates, a precursor state of superconductivity is speculated to exist above the critical temperature TC. Here we show via a combination of far-infrared ellipsometry and ultrafast broadband optical spectroscopy that signatures of such a state can be obtained via three independent observables in an underdoped sample of NdBa2Cu3O6+δ. The pseudogap correlations were disentangled from the response of laser-broken pairs by clocking their characteristic time scales. The onset of a superconducting precursor state was found at a temperature TONS>TC, consistent with the temperature scale identified via static optical spectroscopy. Furthermore, the temperature evolution of the coherent vibration of the Ba ion, strongly renormalized by the onset of superconductivity, revealed a pronounced anomaly at the same temperature TONS. The microscopic nature of such a precursor state is discussed in terms of preformed pairs and enhanced bilayer coherence. application/pdf https://folia.unifr.ch/global/documents/305382 https://folia.unifr.ch/documents/305382/files/ber_cob.pdf https://folia.unifr.ch/documents/305382/files/ber_cob_sm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.95.024501 info:eu-repo/semantics/openAccess License undefined Physical Review B. - 2017, vol. 95, no. 2, p. 024501 info:eu-repo/classification/udc/53 Clocking the onset of bilayer coherence in a high-${T}_{c}$ cuprate http://purl.org/coar/resource_type/c_6501