Metal/SrTiO3 two-dimensional electron gases for spin-to-charge conversion

Luis M. Vicente-Arche, Srijani Mallik, Maxen Cosset-Cheneau, Paul Noël, Diogo C. Vaz, Felix Trier, Tanay A. Gosavi, Chia-Ching Lin, Dmitri E. Nikonov, Ian A. Young, Anke Sander, Agnès Barthélémy, Jean-Philippe Attané, Laurent Vila, and Manuel Bibes
Phys. Rev. Materials 5, 064005 – Published 15 June 2021

Abstract

SrTiO3-based two-dimensional electron gases (2DEGs) can be formed through the deposition of epitaxial oxides like LaAlO3 or of reactive metals such as Al. Such 2DEGs possess a finite Rashba spin-orbit coupling that has recently been harnessed to interconvert charge and spin currents through the direct and inverse Edelstein and spin Hall effects. Here we compare the formation and properties of 2DEGs generated in SrTiO3 by the growth of Al, Ta, and Y ultrathin films by magnetron sputtering. By combining in situ and ex situ x-ray photoelectron spectroscopy (XPS) we gain insight into the reduction of the SrTiO3 and the appearance of Ti3+ states associated with 2DEG formation, its reoxidation by exposure to the air, and the transformation of the metal into its binary oxides. We extract the carrier densities through magnetotransport and compare them with the XPS data. Finally, working with samples covered by an extra layer of NiFe, we perform spin-pumping ferromagnetic resonance experiments and investigate spin-charge conversion as a function of gate voltage. We identify trends in the data across the different sample systems and discuss them as a function of the carrier density and the transparency of the metal oxide tunnel barrier.

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  • Received 9 December 2020
  • Accepted 3 May 2021

DOI:https://doi.org/10.1103/PhysRevMaterials.5.064005

©2021 American Physical Society

Physics Subject Headings (PhySH)

  1. Physical Systems
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Luis M. Vicente-Arche1,*, Srijani Mallik1,*, Maxen Cosset-Cheneau2, Paul Noël2,†, Diogo C. Vaz1,‡, Felix Trier1,§, Tanay A. Gosavi3, Chia-Ching Lin3, Dmitri E. Nikonov3, Ian A. Young3, Anke Sander1, Agnès Barthélémy1, Jean-Philippe Attané2, Laurent Vila2, and Manuel Bibes1

  • 1Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France
  • 2Université Grenoble Alpes, CEA, CNRS, INP, IRIG-Spintec, Grenoble, France
  • 3Components Research, Intel Corporation, Hillsboro, Oregon 97124, USA

  • *These authors contributed equally to this work.
  • Present address: Department of Materials, ETH Zürich, Hönggerbergring 64, 8093 Zürich, Switzerland.
  • Present address: CIC nanoGUNE BRTA, Tolosa Hiribidea, 76, 20018 Donostia, San Sebastian, Spain.
  • §Present address: Department of Energy Conservation and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

See Also

Controlling the electronic interface properties of AlOx/SrTiO3 heterostructures

Berengar Leikert, Judith Gabel, Matthias Schmitt, Martin Stübinger, Philipp Scheiderer, Louis Veyrat, Tien-Lin Lee, Michael Sing, and Ralph Claessen
Phys. Rev. Materials 5, 065003 (2021)

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Vol. 5, Iss. 6 — June 2021

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