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

TL;DR

This paper investigates the connection between a giant phonon anomaly and superconducting fluctuations in the pseudogap phase of cuprates, revealing how phase fluctuations and Leggett modes influence phonon behavior.

Contribution

It introduces a model linking pseudogap-induced Fermi surface breakup to Leggett modes and phonon anomalies in cuprates.

Findings

Large increase in superconducting fluctuation temperature range

Strong phonon damping due to Leggett mode interactions

Phonon dispersion anomalies in the ordered state

Abstract

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.