Incoherent Soliton Excitations and Spin-Charge Separation in Blue Bronze

TL;DR

This paper combines high-resolution ARPES experiments with a novel theoretical model to analyze spin-charge separation and soliton excitations in blue bronze, revealing new spectral features and insights into its quasi-one-dimensional electronic structure.

Contribution

It introduces a new theoretical framework based on ladder spectral properties to explain ARPES data, highlighting spin-charge separation and soliton bound states in blue bronze.

Findings

Observation of broad ARPES lineshape indicating spin-charge separation

Detection of a high-energy feature as a soliton bound state

Confirmation of ladder-like Fermi surface structure

Abstract

We present new high resolution angle resolved photoemission (ARPES) data for K$_{0.3}$MoO$_3$ (blue bronze) and propose a novel theoretical description of these results. The observed Fermi surface, with two quasi-one-dimensional sheets, is consistent with a ladder material with a weak inter-ladder coupling. Hence, we base our description on spectral properties of one-dimensional ladders. The marked broadening of the ARPES lineshape, a significant fraction of an eV, is interpreted in terms of spin-charge separation. A high energy feature, which is revealed for the first time in the spectra near the Fermi momentum thanks to improved energy resolution, is seen as a signature of a higher energy bound state of soliton excitations on a ladder.