title: Giant phonon anomaly associated with superconducting fluctuations in the pseudogap phase of cuprates.
abstract: The pseudogap in underdoped cuprates leads to significant changes in the electronic structure, and was later found to be accompanied by anomalous fluctuations of superconductivity and certain lattice phonons. Here we propose that the Fermi surface breakup due to the pseudogap, leads to a breakup of the pairing order into two weakly coupled sub-band amplitudes, and a concomitant low energy Leggett mode due to phase fluctuations between them. This increases the temperature range of superconducting fluctuations containing an overdamped Leggett mode. In this range inter-sub-band phonons show strong damping due to resonant scattering into an intermediate state with a pair of overdamped Leggett modes. In the ordered state, the Leggett mode develops a finite energy, changing the anomalous phonon damping into an anomaly in the dispersion. This proposal explains the intrinsic connection between the anomalous pseudogap phase, enhanced superconducting fluctuations and giant anomalies in the phonon spectra.
authors.affiliation: Theoretische Physik, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Ye-Hua
authors.identifier: http://orcid.org/0000-0002-1002-399X
authors.initials: YH
authors.lastname: Liu
authors.affiliation: Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Konik
authors.affiliation: Theoretische Physik, ETH Zurich, 8093 Zurich, Switzerland.|Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Rice
authors.affiliation: Department of Physics, Zhejiang University, Hangzhou 310027, China.|Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Fu-Chun
authors.initials: FC
authors.lastname: Zhang