Conducting oxide interfaces

Main researchers: Margherita Boselli, Stefano Gariglio, Adrien Waelchli

The interface between SrTiO3 and a thin film of LaAlO3 hosts a conducting two dimensional electron system (2DES). The 2DES is confined in SrTiO3 within a few nm from its interface with LaAlO3, and originates from the polar discontinuity occurring when a polar insulating material, LaAlO3, is grown on top of a neutral one, SrTiO3.

LaAlO3/SrTiO3 heterostructures have been part of the scientific agenda of our group since the discovery of the conducting interface [1] and, in 2006, we showed that the 2DES is superconducting below ~300 mK [2] and that the superconductivity can be tuned by an external electric field [3]. Very interestingly, top-, back- and side-gates can modify the 2DES carrier density, carrier mobility and the strength of the spin-orbit coupling acting at the interface [4,5].

Our research is now focused on the properties of the 2DES at the nanoscale, on the interplay between superconductivity and ferroelectricity in SrTiO3 and on spintronic effects.

Superconductivity in LAO/STO
Left panel: Temperature behavior of the resistance at different back-gate voltages. By increasing the back-gate from -300 V to 320 V, the 2DES moves from a weak-localization regime to a superconducting phase. Right panel: Sheet resistance at 600 mK as a function of the back-gate plotted together with the superconducting transition temperature [3].

[1]. A. Ohtomo and H. Y. Hwang, Nature 427, (2004)

[2]. N. Reyren et al. Science 317, (2007)

[3]. A. Caviglia et al. Nature 456, (2008)

[4]. M. Ben Shalom et al. Phys. Rev. Lett. 104, (2010)

[5]. D. Stornaiuolo et al. Phys. Rev. B 90, (2014)