Doping-dependent band structure of LaAlO$_{3}$/SrTiO$_{3}$ interfaces by soft x-ray polarization-controlled resonant angle-resolved photoemission

TL;DR

This study uses polarization-controlled resonant photoemission to explore how doping affects the electronic band structure of LaAlO₃/SrTiO₃ interfaces, revealing polarization-dependent Fermi surfaces and orbital contributions.

Contribution

It introduces a polarization-controlled resonant photoemission method to analyze doping-dependent electronic structures of buried interfaces, combining experimental data with first-principle calculations.

Findings

Fermi surface and band dispersions strongly depend on light polarization.

Different doping levels lead to distinct band occupancies and Fermi surface shapes.

Experimental results align with first-principle calculations for various 3d-band fillings.

Abstract

Polarization-controlled synchrotron radiation was used to map the electronic structure of buried conducting interfaces of LaAlO$_3$/SrTiO$_3$ in a resonant angle-resolved photoemission experiment. A strong dependence on the light polarization of the Fermi surface and band dispersions is demonstrated, highlighting the distinct Ti 3d orbitals involved in 2D conduction. Samples with different 2D doping levels were prepared and measured by photoemission, revealing different band occupancies and Fermi surface shapes. A direct comparison between the photoemission measurements and advanced first-principle calculations carried out for different 3d-band fillings is presented in conjunction with the 2D carrier concentration obtained from transport measurements.