Superconducting dome in the LaAlO${}_3$/SrTiO${}_3$ interfaces as a direct effect of the extended s-wave symmetry of the gap

Abstract

The two-dimensional electron gas (2DEG) at the LaAlO${}_3$/SrTiO${}_3$ interface exhibits gate tunable superconductivity with a domelike shape of $T_{\mathrm{C}}$ as a function of electron concentration. Here, we propose that the experimentally observed behavior can be explained as a direct effect of the dominant $extended$ $s$-$wave$ symmetry of the superconducting gap. Our results agree very well with the experimental data. As shown, neither the correlation effects nor the spin-orbit coupling influence significantly the physical picture of the paired state steaming out from our analysis.