Abstract
The interface between the two band insulators SrTiO3 and LaAlO3 has the unexpected 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, that is, Tc has a non-monotonic dependence on Vg, similar to many unconventional superconductors. Here, we report, the frequency of the quantum resistance-oscillations versus inverse magnetic field for various Vg. This frequency follows the same non-monotonic behaviour as Tc; 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.
Highlights
The interface between the two band insulators SrTiO3 and LaAlO3 has the unexpected properties of a two-dimensional electron gas
In this study we use the Shubnikov-de Haas (SdH) effect, as well as the resistivity and the low field limit of the inverse Hall coefficient RHÀ 1, to study the band structure of the SrTiO3/LaAlO3 interface
We show that the SdH frequency and RHÀ 1 follow a non-monotonic behaviour similar to the dependence of the superconducting critical temperature Tc and magnetic field Hc on gate bias
Summary
The interface between the two band insulators SrTiO3 and LaAlO3 has the unexpected properties of a two-dimensional electron gas. We show that the SdH frequency and RHÀ 1 follow a non-monotonic behaviour similar to the dependence of the superconducting critical temperature Tc and magnetic field Hc on gate bias Both the SdH frequency and RHÀ 1 exhibit an anomalous decrease on increasing the gate bias beyond maximum Tc. Both the SdH frequency and RHÀ 1 exhibit an anomalous decrease on increasing the gate bias beyond maximum Tc We interpret this unconventional decrease as arising from electronic correlations between the Ti t2g bands that are mixed by the atomic spin–orbit interaction. Our calculations show that in this case the population of the mobile band and its density of states (DOS) are nonmonotonic functions of the chemical potential (m) This can explain the peculiar gate dependence of the transport properties, as well as the decrease in Tc on the overdoped regime in the (Vg, T) phase diagram
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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
