Superfluid stiffness and superconducting gap of KTaO3-based 2D gas.

ORAL · Invited

Abstract

The achievement of high-quality epitaxial interfaces involving transition metal oxides offers a unique opportunity to design artificial materials that host novel electronic phases. After fifteen years of dedicated research on SrTiO3 -based interfaces [1], the recent discovery of a superconducting 2-DEG) in (111)-oriented KTaO3-based heterostructures injected new momentum into the realm of oxide interfaces [2,3]. In this system, the superconducting Tc can exceed 2K, nearly an order of magnitude higher than that observed in SrTiO3-based interfaces. Additionally, the increased mass of Ta compared to Ti leads to significantly enhanced spin-orbit effects, as recently demonstrated [4,5]. Consequently, KTaO3-based 2-DEGs have the potential to enable the realization of topological superconducting phases—a concept originally proposed for SrTiO3-based 2-DEGs but hitherto unattainable due to the limitations of the relevant energy scales. In this talk, I will present dc and microwave transport experiments on gate tunable superconducting 2-DEGs formed at the (111)-oriented AlOx/KTaO3 interface. The temperature dependence of the superfluid stiffness, extracted from the microwave response of the 2-DEG, is found to be consistent with a node-less superconducting order parameter having a gap value larger than expected within a simple BCS weak-coupling limit model (Δ0/kBTc= 2.3) [6]. Moreover, the superconducting transition follows the Berezinskii-Kosterlitz-Thouless scenario, a phenomenon not previously reported in SrTiO3-based interfaces. In addition, I will also present recent measurements of the superconducting gap obtained via tunneling spectroscopy in Au/AlOx/(111)-KTaO3 planar junctions and discuss its temperature dependence and evolution under a perpendicular magnetic field. Finally, I will provide perspectives on the realization of superconducting devices

References

[1] A. Caviglia et al., Nature 456, 624–627 (2008).[2] Liu, C. et al. Science 371, 716–721 (2021).

[3] Chen, Z. et al. Science 372, 721–724 (2021).

[4] Vicente-Arche, L. M. et al. Adv. Mater. 2102102 (2021).

[5] S. Varotto, et al. Nature Commun. 13, 6165 (2022).

[6] S. Mallik et al. Nature Commun. 13, 4625 (2022)

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Publication: S. Mallik et al. Nature Commun. 13, 4625 (2022).

Presenters

  • Nicolas Bergeal

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

Authors

  • Nicolas Bergeal

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

  • Srijani Mallik

    Universite Paris-Saclay, Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau

  • Gerbold C Ménard

    ESPCI Paris

  • Guilhem Saiz

    Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, Université PSL, CNRS, Sorbonne Université, Paris, ESPCI Paris, Universite PSL, CNRS, Sorbonne Universite, Paris, France, ESPCI Paris

  • Hugo Witt

    Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, Unité Mixte de Physique CNRS-Thales

  • Jerome Lesueur

    ESPCI Paris

  • Alexandre Gloter

    Laboraotire de Physique des Solides, Université Paris Saclay

  • Lara Benfatto

    Sapienza University of Rome

  • Manuel Bibes

    CNRS/THALES, Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau