Band-selective Holstein polaron in Luttinger liquid material A0.3MoO3 (A = K, Rb)

TL;DR

This study reveals that A0.3MoO3 exhibits Luttinger liquid behavior with strong electron-phonon interactions leading to Holstein polarons, influencing charge-density-wave formation and electronic properties in quasi-one-dimensional systems.

Contribution

It provides experimental evidence of Holstein polarons in a Luttinger liquid material and highlights the role of electron-phonon coupling in charge-density-wave transitions.

Findings

Observation of band renormalization consistent with Holstein polarons

Identification of strong electron-phonon coupling in A0.3MoO3

Reconciliation of long-standing debates on blue bronze electronic properties

Abstract

(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A0.3MoO3 (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A0.3MoO3 is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which is recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays a dominant role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study novel composite quasiparticles in Luttinger liquid materials.