open access publication

Article, 2022

Current Mapping of Amorphous LaAlO3/SrTiO3 near the Metal–Insulator Transition

ACS Applied Electronic Materials, ISSN 2637-6113, Volume 4, 7, Pages 3421-3427, 10.1021/acsaelm.2c00264

Contributors

Bjørlig, Anders V 0000-0003-4583-4706 [1] Christensen, Dennis Valbjørn 0000-0003-0048-7595 [2] Erlandsen, Ricci 0000-0002-7115-0618 [2] Pryds, Nini 0000-0002-5718-7924 [2] Kalisky, Beena 0000-0002-1270-2670 (Corresponding author) [1]

Affiliations

  1. [1] Bar-Ilan University
    2. [NORA names: Israel; Asia, Middle East; OECD];
  2. [2] Technical University of Denmark
    3. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD]

Abstract

The two-dimensional electron system found between LaAlO3 and SrTiO3 hosts a variety of physical phenomena that can be tuned through external stimuli. This allows for electronic devices controlling magnetism, spin–orbit coupling, and superconductivity. Controlling the electron density by varying donor concentrations and using electrostatic gating are convenient handles to modify the electronic properties, but the impact on the microscopic scale, particularly of the former, remains underexplored. Here, we image the current distribution at 4.2 K in amorphous-LaAlO3/SrTiO3 using scanning superconducting quantum interference device microscopy while changing the carrier density in situ using electrostatic gating and oxygen annealing. We show how potential disorder affects the current and how homogeneous 2D flow evolves into several parallel conducting channels when approaching the metal-to-insulator transition. We link this to ferroelastic domains and oxygen vacancies. This has important consequences for micro- and nanoscale devices with low carrier density and fundamental studies on quantum effects in oxides.

Keywords

LaAlO3, LaAlO3/SrTiO3, SrTiO3, SrTiO3 host, annealing, carrier density, carriers, concentration, consequences, coupling, density, density in situ, devices, disorders, distribution, domain, donor, donor concentration, effect, electron, electron density, electronic properties, electronic systems, electrostatic gating, external stimuli, ferroelastic domains, flow, gate, host, impact, low carrier density, magnetization, maps, metal-insulator, metal-insulator transition, metal-to-insulator transition, micro-, microscopic scale, microscopy, nanoscale, nanoscale devices, oxidation, oxygen, oxygen annealing, oxygen vacancies, phenomenon, physical phenomena, properties, quantum effects, quantum interference device microscopy, scale, scanning superconducting quantum interference device microscopy, spin-orbit coupling, stimuli, superconductivity, system, transition, two-dimensional electron system, vacancies

Funders

  • Danish Ministry of Higher Education and Science
  • European Research Council
  • Novo Nordisk Foundation
  • Israel Science Foundation
  • European Commission
  • The Velux Foundations

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