Observable Zero Sound in Strongly Correlated Metals

TL;DR

This paper demonstrates that zero-sound modes in strongly correlated, charged 2D Fermi systems persist near the Mott transition and soften at the transition point, potentially causing structural changes similar to those in oxide superconductors.

Contribution

It reveals the persistence and softening of zero-sound modes in charged systems near the Mott transition, linking them to structural transitions in oxides.

Findings

Zero-sound mode persists at the Mott transition in charged systems.

Sound velocity softens completely at the transition point.

Potential connection to structural transitions in oxide superconductors.

Abstract

The slow zero-sound mode expected near the Mott transition in strongly interacting two-dimensional Fermi systems that are neutral is shown to persist as the physical sound mode in the case that the fermion carries electronic charge and is embedded in a positive ionic background. The latter sound velocity softens completely precisely at the Mott transition, indicating that a zone-center structural transition will occur in the system. We suggest that this phonon-softening mechanism is related to the structural transitions commonly observed in the oxide superconductors.