Modulation of Spin-Orbit interaction and superconductivity in two-dimensional electron gas at the Mott-Insulator - Band-Insulator interface: LaTiO3 - SrTiO3

It has been shown recently that a two-dimensional electron gas could form at the interface of two insulators such as LaAlO$_{3}$ and SrTiO$_{3}$ [1], or LaTiO$_{3}$ (a Mott insulator) and SrTiO$_{3}$ [2]. We present low temperature transport and magneto-transport measurements on LaTiO$_{3}$/SrTiO$_{3}$ hetero-structures, whose properties can be modulated by field effect using a metallic gate on the back of the substrate. The corresponding phase diagram has been investigated, and superconductivity evidenced for the first time in this system which involves a Mott insulator [3]. We will discuss the role of the confinement potential and the SrTiO$_{3}$ band structure on the phase diagram, and show the specific role of the spin-orbit coupling measured by localization corrections to the magnetoconductivity. Finally, the superconducting to insulator transition will be analyzed. [1] N. Reyren et al, Science 317, 1196 (2007) [2] A. Ohtomo et al, Nature 419, 378 (2002) [3] J. Biscaras et al, Nature Commun, DOI: 10.1038/ncomms1084 (2010)