Novel two-dimensional electron systems at the interfaces and surfaces of transition-metal oxides recently have attracted much attention as they display tunable, intriguing properties that can be exploited in future electronic devices. Here we show that a high-mobility quasi-two-dimensional electron system with strong spin-orbit coupling can be induced at the surface of a KTaO3 (001) crystal by pulsed laser deposition of a disordered LaAlO3 film. The momentum-resolved electronic structure of the buried electron system is mapped out by hard x-ray angle-resolved photoelectron spectroscopy. From a comparison to calculations it is found that the band structure deviates from that of electron-doped bulk KTaO3 due to the confinement to the interface. Nevertheless, the Fermi surface appears to be clearly three-dimensional. From the k broadening of the Fermi surface and core-level depth profiling we estimate the extension of the electron system to be at least 1 nm but not much larger than 2 nm, respectively.
@article{arxiv.2110.15158,
title = {Hard x-ray angle-resolved photoemission from a buried high-mobility electron system},
author = {Michael Zapf and Matthias Schmitt and Judith Gabel and Philipp Scheiderer and Martin Stübinger and Berengar Leikert and Giorgio Sangiovanni and Lenart Dudy and Sergii Chernov and Sergey Babenkov and Dmitry Vasilyev and Olena Fedchenko and Katerina Medjanik and Yury Matveyev and Andrei Gloskowski and Christoph Schlueter and Tien-Lin Lee and Hans-Joachim Elmers and Gerd Schönhense and Michael Sing and Ralph Claessen},
journal= {arXiv preprint arXiv:2110.15158},
year = {2022}
}