Polarization sensitive surface band structure of doped BaTiO3(001)

TL;DR

This study investigates the surface electronic structure of doped BaTiO3(001) using spatially and wave-vector resolved photoemission, revealing polarization-dependent features and a surface phase transition influenced by doping levels.

Contribution

It provides new experimental evidence of surface ferroelectric-paraelectric transition and polarization states in doped BaTiO3(001) using advanced photoemission techniques.

Findings

Surface phase transition observed below critical doping.

Presence of in-plane and out-of-plane polarization confirmed.

Results align with first principles calculations.

Abstract

We present a spatial and wave-vector resolved study of the electronic structure of micron sized ferroelectric domains at the surface of a BaTiO3(001) single crystal. The n-type doping of the BaTiO3 is controlled by in-situ vacuum and oxygen annealing, providing experimental evidence of a surface paraelectric-ferroelectric transition below a critical doping level. Real space imaging of photoemission threshold, core level and valence band spectra show contrast due to domain polarization. Reciprocal space imaging of the electronic structure using linearly polarized light provides unambiguous evidence for the presence of both in and out-of plane polarization with two and fourfold symmetry, respectively. The results agree well with first principles calculations.