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Quantized conductance in a one-dimensional ballistic oxide nanodevice

Nature Electronics volume 3, pages 201–206 (2020)Cite this article

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Abstract

The electric-field effect control of two-dimensional electron gases (2-DEGs) has allowed nanoscale electron quantum transport to be explored in semiconductors. Structures based on transition metal oxides have electronic states that favour the emergence of novel quantum orders that are absent in conventional semiconductors and the 2-DEG formed at a LaAlO3/SrTiO3 interface—a structure in which superconductivity and spin–orbit coupling can coexist—is a promising platform to develop devices for spintronics and topological electronics. However, field-effect control of the properties of this interface at the nanoscale remains challenging. Here we show that a quantum point contact can be formed in a LaAlO3/SrTiO3 interface through electrostatic confinement of the 2-DEG using a split gate. Our device exhibits a quantized conductance due to ballistic transport in a controllable number of one-dimensional conducting channels. Under a magnetic field, the direct observation of the Zeeman splitting between spin-polarized bands allows the determination of the Landé g-factor, whose value differs strongly from that of the free electrons. Through source–drain voltage measurements, we also performed a spectroscopic investigation of the 3d energy levels inside the quantum point contact. The LaAlO3/SrTiO3 quantum point contact could potentially be used as a spectrometer to probe Majorana states in an oxide 2-DEG.

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Fig. 1: Schematic description of the QPC device.
Fig. 2: Ballistic transport and conductance quantization.
Fig. 3: Spectroscopy of the QPC sub-bands.
Fig. 4: Zeeman splitting and spin-polarized sub-bands under a magnetic field.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

We acknowledge M. Aprili, A. Caviglia, A. Akhmerov, R. Citro, M. Grilli, S. Caprara and L. Benfatto for stimulating discussions. This work was supported by the French RENATECH network (French national nanofabrication platform), the Région Ile-de-France in the framework of C’Nano IdF, OXYMORE and Sesame programs, by CNRS through a Projet International de Coopération Scientifique (PICS) programme and by the Agence Nationale de la Recherche (ANR) Projet de Recherche Collaborative (PRC) (QUANTOP). We acknowledge funding received from the project Quantox of QuantERA ERA-NET Cofund in Quantum Technologies (Grant Agreement no. 731473) implemented within the European Union’s Horizon 2020 Program. The authors also acknowledge the European Cooperation in Science and Technology (COST) project Nanoscale coherent hybrid devices for superconducting quantum technologies Action CA16218.

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Authors and Affiliations

  1. Laboratoire de Physique et d’Etude des Matériaux, ESPCI Paris, PSL University, CNRS, Sorbonne Université, Paris, France

    A. Jouan, G. Singh, S. Hurand, J. Lesueur, C. Feuillet-Palma & N. Bergeal

  2. Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience MC2, Chalmers University of Technology, Gothenburg, Sweden

    G. Singh

  3. Unité Mixte de Physique CNRS-Thales, Université Paris-Sud/Université Paris-Saclay, Palaiseau, France

    E. Lesne, D. C. Vaz, M. Bibes & A. Barthélémy

  4. Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Sud/Université Paris-Saclay, Palaiseau, France

    C. Ulysse

  5. Department of Physics, University of Naples Federico II Complesso Monte S. Angelo, Napoli, Italy

    D. Stornaiuolo

  6. CNR-SPIN Complesso Monte S. Angelo, Napoli, Italy

    D. Stornaiuolo & M. Salluzzo

  7. Institut Pprime, UPR 3346 CNRS, Université de Poitiers, ISAE-ENSMA, Chasseneuil, France

    S. Hurand

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  1. A. Jouan
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Contributions

A.J. and G.S. performed the measurements under the supervision of N.B. Samples were fabricated by E.L. and D.C.V. under the supervision of A.B. and M.B. Nanofabrication processes were performed by A.J. and C.U. A.J., G.S., C.F.-P., J.L. and N.B. carried out the analysis of the results. A.J. and N.B. wrote the Article with the help of J.L. M.S. and M.B. All the authors contributed to discussions of the results and commented on the final manuscript.

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Correspondence to N. Bergeal.

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Supplementary Sections 1–5, Figs. 1–4 and refs. 1–2.

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Jouan, A., Singh, G., Lesne, E. et al. Quantized conductance in a one-dimensional ballistic oxide nanodevice. Nat Electron 3, 201–206 (2020). https://doi.org/10.1038/s41928-020-0383-2

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