Nature of Superconductor-Insulator Transition at LaAlO3/SrTiO3 Interface

The two-dimensional electron liquid, at the interface between two band insulators LaAlO3 and SrTiO3, exhibits novel, unconventional superconductivity below 200 mK. One of the remarkable properties of the two-dimensional superconductor is its fantastic tunability by external parameters such as gate-voltage or magnetic field. We study the superconductor to insulator transition induced by gate-voltage by employing a self-consistent, mean-field Bogoliubov-de Gennes treatment based on an effective model. We show that the non-monotonic behaviour of the superconductivity with respect to gate-voltage is intrinsically due to the Rashba spin-orbit coupling. With increasing gate-voltage both the electron concentration and Rashba spin-orbit splitting increases. Elevated electron filling boosts superconductivity whereas enhanced spin-orbit splitting annihilates electron-pairing. The non-monotonicity is a result of this competition. The device application of the superconductor-insulator transition in this interface is discussed.