Giant Phonon Anomaly associated with Superconducting Fluctuations in the Pseudogap Phase of Cuprates


Abstract in English

The opening of the pseudogap in underdoped cuprates breaks up the Fermi surface, which may lead to a breakup of the d-wave order parameter into two subband amplitudes and a low energy Leggett mode due to phase fluctuations between them. This causes a large increase in the temperature range of superconducting fluctuations with an overdamped Leggett mode. Almost resonant scattering of inter-subband phonons to a state with a pair of Leggett modes causes anomalously strong damping. In the ordered state, the Leggett mode develops a finite energy, suppressing the anomalous phonon damping but leading to an anomaly in the phonon dispersion.

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