Alternative route to charge density wave formation in multiband systems

TL;DR

This paper demonstrates that enhanced electron-lattice interactions, especially near band degeneracy points, can influence charge density wave formation in multiband systems, challenging the traditional Fermi surface topology explanation.

Contribution

It introduces an alternative mechanism involving electron-phonon coupling for charge density wave formation, supported by combined experimental and theoretical analysis.

Findings

Enhanced electron-phonon interactions influence CDW vector selection.

Relation established between light scattering spectra and electron-phonon coupling.

Potential relevance for phase transitions in multiband systems like iron-based superconductors.

Abstract

Charge and spin density waves, periodic modulations of the electron and magnetization densities, respectively, are among the most abundant and non-trivial low-temperature ordered phases in condensed matter. The ordering direction is widely believed to result from the Fermi surface topology. However, several recent studies indicate that this common view needs to be supplemented. Here, we show how an enhanced electron-lattice interaction can contribute to or even determine the selection of the ordering vector in the model charge density wave system ErTe3. Our joint experimental and theoretical study allows us to establish a relation between the selection rules of the electronic light scattering spectra and the enhanced electron-phonon coupling in the vicinity of band degeneracy points. This alternative proposal for charge density wave formation may be of general relevance for driving phase transitions into other broken-symmetry ground states, particularly in multiband systems such as the iron based superconductors.