Strong correlations elucidate the electronic structure and phase diagram of LaAlO(3)/SrTiO(3) interface

The interface between the two band insulators SrTiO(3) and LaAlO(3) has the unexpected properties of a two-dimensional electron gas. It is even superconducting with a transition temperature, T(c), that can be tuned using gate bias V(g), which controls the number of electrons added or removed from the interface. The gate bias–temperature (V(g), T) phase diagram is characterized by a dome-shaped region where superconductivity occurs, that is, T(c) has a non-monotonic dependence on V(g), similar to many unconventional superconductors. Here, we report, the frequency of the quantum resistance-oscillations versus inverse magnetic field for various V(g). This frequency follows the same non-monotonic behaviour as T(c); a similar trend is seen in the low field limit of the Hall coefficient. We theoretically show that electronic correlations result in a non-monotonic population of the mobile band, which can account for the experimental behaviour of the normal transport properties and the superconducting dome.