Hard x-ray angle-resolved photoemission from a buried high-mobility electron system

M. Zapf, M. Schmitt, J. Gabel, P. Scheiderer, M. Stübinger, B. Leikert, G. Sangiovanni, L. Dudy, S. Chernov, S. Babenkov, D. Vasilyev, O. Fedchenko, K. Medjanik, Yu. Matveyev, A. Gloskowski, C. Schlueter, T.-L. Lee, H.-J. Elmers, G. Schönhense, M. Sing, and R. Claessen
Phys. Rev. B 106, 125137 – Published 21 September 2022

Abstract

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. Fermi surface mapping shows a three-dimensional, periodic intensity pattern consistent with electron pockets of quantum well states centered around the Γ points and the expectations from a Fourier analysis-based description of photoemission on confined electron systems. 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.

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  • Received 3 November 2021
  • Revised 13 June 2022
  • Accepted 7 September 2022

DOI:https://doi.org/10.1103/PhysRevB.106.125137

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

M. Zapf1, M. Schmitt1,*, J. Gabel1,2, P. Scheiderer1, M. Stübinger1, B. Leikert1, G. Sangiovanni3, L. Dudy1,4, S. Chernov5, S. Babenkov5, D. Vasilyev5, O. Fedchenko5, K. Medjanik5, Yu. Matveyev6, A. Gloskowski6, C. Schlueter6,2, T.-L. Lee2, H.-J. Elmers5, G. Schönhense5, M. Sing1, and R. Claessen1

  • 1Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Julius-Maximilians-Universität, 97074 Würzburg, Germany
  • 2Diamond Light Source Ltd., Didcot, Oxfordshire OX11 0DE, United Kingdom
  • 3Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Julius-Maximilians-Universität, 97074 Würzburg, Germany
  • 4SOLEIL Synchrotron, 91190 Saint-Aubin, France
  • 5Insitut für Physik, Johannes Gutenberg-Universität, 55122 Mainz, Germany
  • 6DESY Photon Science, 22607 Hamburg, Germany

  • *mschmitt@physik.uni-wuerzburg.de

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Issue

Vol. 106, Iss. 12 — 15 September 2022

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