Strong correlations elucidate the electronic structure and phase-diagram of LaAlO3/SrTiO3 interface

TL;DR

This paper investigates the LaAlO3/SrTiO3 interface, revealing how electronic correlations influence its superconducting properties and phase diagram, with experimental and theoretical insights into the non-monotonic behavior of transport phenomena.

Contribution

It demonstrates that electronic correlations cause non-monotonic band population, explaining the superconducting dome and transport properties at the interface.

Findings

Quantum resistance-oscillation frequency varies non-monotonically with gate bias.

Hall coefficient shows similar non-monotonic behavior.

Electronic correlations explain the superconducting dome.

Abstract

The interface between the two band insulators SrTiO3 and LaAlO3 unexpectedly has the properties of a two dimensional electron gas. It is even superconducting with a transition temperature, Tc, that can be tuned using gate bias Vg, which controls the number of electrons added or removed from the interface. The gate bias - temperature (Vg, T) phase diagram is characterized by a dome-shaped region where superconductivity occurs, i.e., Tc has a non-monotonic dependence on Vg, similar to many unconventional superconductors. In this communication the frequency of the quantum resistance-oscillations versus inverse magnetic field is reported for various Vg. This frequency follows the same nonmonotonic behavior as Tc; 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 behavior of the normal transport properties and the superconducting dome.