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Two-gap s±-wave superconductivity at an oxide interface

G. Singh, G. Venditti, G. Saiz, G. Herranz, F. Sánchez, A. Jouan, C. Feuillet-Palma, J. Lesueur, M. Grilli, S. Caprara, N. Bergeal

DOI 10.1103/PhysRevB.105.064512 · Physical Review B

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Abstract

After half a century of debate, superconductivity in doped SrTiO3 has come to the fore again with the discovery of interfacial superconductivity in the LaAlO3 /SrTiO3 heterostructures. While these interfaces share the interesting properties of bulk SrTiO3 , quantum confinement generates a complex band structure involving bands with different orbital symmetries whose occupancy is tunable by electrostating doping. Multigap superconductivity has been predicted to emerge in LaAlO3 /SrTiO3 at large doping, with a Bose-Einstein condensation character at the Lifshtiz transition. In this article, we report on the measurement of the upper critical magnetic field Hc2 of superconducting (110)-oriented LaAlO3 /SrTiO3 heterostructures and evidence a two-gap superconducting regime at high doping. Our results are quantitatively explained by a theoretical model based on the formation of an unconventional s±-wave superconducting state with a repulsive coupling between the two condensates.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
LaAlO3/SrTiO3

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—Pressure not reportedunknown
SrTiO3

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—Pressure not reportedunknown
MgB2

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—Pressure not reportedunknown

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