Photoemission study of the electronic structure and charge density waves of Na2Ti2Sb2O

TL;DR

This study uses ARPES to analyze the electronic structure and charge density waves in Na2Ti2Sb2O, revealing its weak electronic correlations, multi-band nature, two-dimensionality, and a density wave gap below the transition temperature.

Contribution

First ARPES investigation of Na2Ti2Sb2O revealing its electronic structure, multi-band features, and charge density wave characteristics.

Findings

Electronic structure matches non-magnetic calculations

Weak electronic correlations indicated

Density wave gap of 65 meV at 7 K

Abstract

The electronic structure of Na2Ti2Sb2O, a parent compound of the newly discovered titanium-based oxypnictide superconductors, is studied by photon energy and polarization dependent angle-resolved photoemission spectroscopy (ARPES). The obtained band structure and Fermi surface agree well with the band structure calculation of Na2Ti2Sb2O in the non-magnetic state, which indicating that there is no magnetic order in Na2Ti2Sb2O and the electronic correlation is weak. Polarization dependent ARPES results suggest the multi-band and multi-orbital nature of Na2Ti2Sb2O. Photon energy dependent ARPES results suggest that the electronic structure of Na2Ti2Sb2O is rather two-dimensional. Moreover, we find a density wave energy gap forms below the transition temperature and reaches 65 meV at 7 K, indicating that Na2Ti2Sb2O is likely a weakly correlated CDW material in the strong electron-phonon interaction regime.