Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices

TL;DR

This study investigates the electronic properties of SrTiO3/LaTiO3 superlattices, revealing an electronic reconstruction at the interface and showing how annealing affects spectral features, supported by theoretical calculations.

Contribution

It provides experimental evidence of electronic reconstruction at SrTiO3/LaTiO3 interfaces and demonstrates how annealing modifies spectral weight, supported by layer dynamical-mean-field-theory calculations.

Findings

Finite coherent spectral weight observed at interfaces.

Annealing reduces incoherent spectral part and enhances coherent part.

Theoretical calculations reproduce experimental spectral features.

Abstract

We have measured photoemission spectra of SrTiO3/LaTiO3 superlattices with a topmost SrTiO3 layer of variable thickness. Finite coherent spectral weight with a clear Fermi cut-off was observed at chemically abrupt SrTiO3/LaTiO3 interfaces, indicating that an ``electronic reconstruction'' occurs at the interface between the Mott insulator LaTiO3 and the band insulator SrTiO3. For SrTiO3/LaTiO3 interfaces annealed at high temperatures (~ 1000 C), which leads to Sr/La atomic interdiffusion and hence to the formation of La1-xSrxTiO3-like material, the intensity of the incoherent part was found to be dramatically reduced whereas the coherent part with a sharp Fermi cut-off is enhanced due to the spread of charge. These important experimental features are well reproduced by layer dynamical-mean-field-theory calculation.