Abstract
After half a century of debate, superconductivity in doped ${\mathrm{SrTiO}}_{3}$ has come to the fore again with the discovery of interfacial superconductivity in the ${\mathrm{LaAlO}}_{3} /{\mathrm{SrTiO}}_{3}$ heterostructures. While these interfaces share the interesting properties of bulk ${\mathrm{SrTiO}}_{3}$ , 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 ${\mathrm{LaAlO}}_{3} /{\mathrm{SrTiO}}_{3}$ 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 ${\mathrm{H}}_{\mathrm{c}2}$ of superconducting (110)-oriented ${\mathrm{LaAlO}}_{3} /{\mathrm{SrTiO}}_{3}$ 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 ${\mathrm{s}}_{\ifmmode\pm\else\textpm\fi{}}$-wave superconducting state with a repulsive coupling between the two condensates.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call