The case for the bulk nature of the spectroscopic Luttinger liquid signatures observed in angle resolved photoemission of Li0.9Mo6O17

TL;DR

This study demonstrates that the spectroscopic signatures of a Luttinger liquid observed in ARPES measurements of Li0.9Mo6O17 are intrinsic bulk properties, confirmed across different photon energies and consistent with the material's crystal structure.

Contribution

The paper provides evidence that the Luttinger liquid behavior observed in ARPES is a bulk property of Li0.9Mo6O17, not just a surface phenomenon, based on consistent results at different photon energies.

Findings

ARPES spectra match Luttinger liquid theory with anomalous exponent 0.6

Consistent results at 30 eV and 500 eV photon energies

Spectroscopic LL behavior is a bulk property, not surface-limited

Abstract

Angle resolved photoemission spectroscopy (ARPES) has been performed on quasi-one dimensional Li0.9Mo6O17 using photon energy 500 eV. Measured band dispersions are in agreement with those from both low photon energy measurements and band structure calculations. The momentum integrated ARPES spectrum is well fit by the finite temperature Luttinger liquid (LL)spectral function, with an anomalous exponent 0.6 that is the same within experimental uncertainty as the value found with photon energy 30 eV. These identical findings at both low and high photon energies are entirely consistent with reasoning based on the crystal structure, that the quasi-one dimensional chains lie two layers below the cleavage plane so that the observed spectroscopic LL behavior of Li0.9Mo6O17 is a bulk property.