Condensed-Matter Physics & Materials Science Seminar

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

Presented by Yehua Liu, ETH, Switzerland

Thursday, September 24, 2015, 1:30 pm — Bldg 734, 2nd Fl Conference Room

Recent observations of a Giant Phonon Anomaly at the onset of the pseudogap, has revealed another surprising property of this phase. The opening of the pseudogap in underdoped cuprates breaks up the Fermi surface, which in turn can cause a breakup of the superconducting d-wave order parameter into two subband amplitudes and to a low energy Leggett mode due to phase fluctuations between them. This leads to a large increase in the temperature range of superconducting fluctuations due to an overdamped Leggett mode. Almost resonant scattering of intersubband phonons to a state with a pair of Leggett modes, causes anomalously strong phonon 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.

Hosted by: Robert Konik

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