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  • Letter
  • Open Access

Two-dimensional electron gas at the (001) surface of ferromagnetic EuTiO3

R. Di Capua1,2,*, M. Verma3, M. Radović4, N. C. Plumb4, J. H. Dil4,5, Z. Ristić6, E. B. Guedes4,5, G. M. De Luca1,2, D. Preziosi7 et al.

Z. Wang4, A. P. Weber4,5, R. Pentcheva3, and M. Salluzzo2,†

  • 1Dipartimento di Fisica “Ettore Pancini” Università di Napoli “Federico II”, Complesso Monte-Santangelo via Cinthia, I-80126 Napoli, Italy
  • 2CNR-SPIN Complesso Monte-Santangelo via Cinthia, I-80126 Napoli, Italy
  • 3Department of Physics and Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
  • 4Photon Science Division, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
  • 5Institute of Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
  • 6Vinča Institute of Nuclear Sciences, 11000 Belgrade, Serbia
  • 7Université de Strasbourg, CNRS, IPCMS UMR 7504, 67034 Strasbourg, France

  • *roberto.dicapua@unina.it
  • †marco.salluzzo@spin.cnr.it
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Phys. Rev. Research 3, L042038 – Published 10 December, 2021

DOI: https://doi.org/10.1103/PhysRevResearch.3.L042038

Abstract

Studies on oxide quasi-two-dimensional electron gas (q2DEG) have been a playground for the discovery of novel and sometimes unexpected phenomena, like the reported magnetism at the surface of SrTiO3 (001) and at the interface between nonmagnetic LaAlO3 and SrTiO3 band insulators. However, magnetism in this system is weak and there is evidence of a nonintrinsic origin. Here, by using in situ high-resolution angle-resolved photoemission, we demonstrate that ferromagnetic EuTiO3, the magnetic counterpart of SrTiO3 in the bulk, hosts a q2DEG at its (001) surface. This is confirmed by density functional theory calculations with Hubbard U terms in the presence of oxygen divacancies in various configurations, all of them leading to a spin-polarized q2DEG related to the ferromagnetic order of Eu-4f magnetic moments. The results suggest EuTiO3(001) as a new material platform for oxide q2DEGs, characterized by broken inversion and time-reversal symmetries.

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Phys. Rev. Research 3, L042038– Published 10 December, 2021
  • Received 23 December 2020
  • Accepted 25 October 2021
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