Origin of dimensional crossover in quasi-one-dimensional hollandite K$_{2}$Ru$_{8}$O$_{16}$

TL;DR

This study combines experimental and theoretical methods to investigate the electronic structure of K₂Ru₈O₁₆, revealing a temperature-induced crossover from one-dimensional to three-dimensional electronic behavior driven by electron correlations and thermal effects.

Contribution

It provides the first comprehensive analysis of the dimensional crossover in hollandite K₂Ru₈O₁₆ using combined photoemission spectroscopy and advanced theoretical modeling.

Findings

Identification of Tomonaga-Luttinger liquid behavior down to 150 K

Observation of a dimensional crossover to 3D electronic behavior at lower temperatures

Demonstration that Fermi surface warping influences the crossover mechanism

Abstract

Intriguing phenomenon of dimensional crossover is comprehensively studied by experimental and theoretical investigation of electronic structure in quasi-one-dimensional hollandite K$_{2}$Ru$_{8}$O$_{16}$. Valence band photoemission spectra in conjunction with density functional theory within local density approximation combined with dynamical mean field theory (LDA+DMFT) reveal moderately correlated electronic structure. Anomalous temperature dependence of high-resolution spectra in the vicinity of Fermi level suggests Tomonaga-Luttinger liquid state down to 150 K, below which it undergoes a dimensional crossover from one-dimensional to three-dimensional electronic behaviour. Monotonously decreasing spectral intensity at the Fermi level along with Fermi cut-off at low temperature suggests non-Fermi liquid like behaviour. Many body effects captured within LDA+DMFT reveal increased warping of the Fermi surface with lowering temperature. A simple analysis suggests that the warping dominates the thermal energy induced momentum broadening at low temperature, leading to the 3D electronic behaviour. Our results offer valuable insight in understanding the interplay of dimensionality, electron correlation and thermal energy governing various exotic phenomena in quasi-one-dimensional systems.