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Jeudi 2 décembre 2010, 16h00
Amphi Boreau, Esc C, 2ème etage
Transport properties of superconducting two-dimensional electron gas at the Mott-Insulator/Band-Insulator LaTiO3/SrTiO3 interface
Transition metal oxides display a great variety of quantum electronic behaviors where correlations often play an important role. The achievement of high quality epitaxial interfaces involving such materials gives a unique opportunity to engineer artificial materials where new electronic orders take place. It has been shown recently that a two-dimensional electron gas could form at the interface of two insulators such as LaAlO3 and SrTiO3 [1], or LaTiO3 (a Mott insulator) and SrTiO3 [2].
We present low temperature transport and magneto-transport measurements on LaTiO3/SrTiO3 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 SrTiO3 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)
