Tunable superconductivity at the oxide-insulator/KTaO${}_3$ interface and its origin

Abstract

Superconductivity forms out of the condensation of Cooper pairs of electrons. The mechanism by which Cooper pairs are created in non-conventional superconductors is often elusive because experimental signatures that connect a specific pairing mechanism to the properties of superconducting state are rare. The recently discovered superconducting oxide-insulator/KTaO${}_3$ interface may offer clues about its origins. Here we observe distinct dependences of the superconducting transition temperature Tc on carrier density n${}_{2D}$ for electron gases formed at KTaO${}_3$ (111), (001) and (110) interfaces. For the KTaO${}_3$ (111) interface, a remarkable linear dependence of Tc on n${}_{2D}$ is observed over a range of nearly one order of magnitude. Further, our study of the dependence of superconductivity on gate electric fields reveals the role of the interface in mediating superconductivity, which also allows for a reversible electric switching of superconductivity at T = 2 K. We found that the extreme sensitivity of superconductivity to crystallographic orientation can be explained by Cooper pairing via inter-orbital interactions induced by the inversion-breaking transverse optical (TO1) phonons and quantum confinement. This mechanism is also consistent with the dependence of Tc on n${}_{2D}$ at the KTaO${}_3$ (111) interface. Our study may shed light on the pairing mechanism in other superconducting quantum-paraelectrics.

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Cited by in corpus (26)

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• Spontaneous rotational symmetry breaking in KTaO${}_3$ heterointerface superconductors
• Enhanced Critical Field of Superconductivity at an Oxide Interface
• Orientation-dependent electron-phonon coupling in interfacial superconductors LaAlO3/KTaO3
• Advances in Complex Oxide Quantum Materials Through New Approaches to Molecular Beam Epitaxy
• Generalized Rashba Electron-Phonon Coupling and Superconductivity in Strontium Titanate
• Anisotropic Electronic Structure of the Two-Dimensional Electron Gas at the AlOx/KTaO3(110) interface
• Terahertz ionic Kerr effect: Two-phonon contribution to the nonlinear optical response in insulators
• Superconductivity at epitaxial LaTiO3-KTaO3 interfaces
• Flux-flow instability across Berezinskii Kosterlitz Thouless phase transition in KTaO${}_3$ (111) based superconductor
• Superconducting quantum oscillations and anomalous negative magnetoresistance in a honeycomb nanopatterned oxide interface superconductor
• Revealing subterahertz atomic vibrations in quantum paraelectrics by surface-sensitive spintronic terahertz spectroscopy
• High stability 2D electron gases formed in Si3N4/Al//KTaO3 heterostructures: synthesis and in-depth interfacial characterization
• Orbital-selective metal skin induced by alkali-metal-dosing Mott-insulating Ca${}_2$RuO${}_4$
• Nonlinear diode effect and Berezinskii-Kosterlitz-Thouless transition in purely two-dimensional noncentrosymmetric superconductors
• Electron Interactions in Rashba Materials
• Phonon-Induced Collective Modes in Spin-Orbit Coupled Polar Metals
• Violation of Pauli Limit at KTaO3(110) Interfaces
• Anisotropic vortex motion and two-dimensional superconducting transition
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• Geometric Control of Pairing: Universal Scaling of Superconductivity at KTaO3 Interfaces
• Chemical control of polymorphism and ferroelectricity in PbTiO3 and SrTiO3 monolayers and bilayers