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Superconductivity at the interface between two insulators

A team of physicists of the Laboratoire de Physique et d’Etude des Matériaux - (CNRS/ESPCI-ParisTech/UPMC), the Laboratoire National des Champs Magnétiques Intenses (CNRS/INSA Toulouse/Univ. Toulouse 3/Univ. Grenoble 1) and the Department of Physics of the Kanpur University (India) have shown that at the interface between the two insulting oxides LaTiO3 and SrTiO3 a two dimensional electron gas exists which shows superconductivity that can be controlled by an electric field.

Below a critical temperature of about 300 mK, this gas condenses into a superconducting state, with zero electrical resistance. By means of Hall effect measurements using the very high magnetic fields of the LNCMI in Toulouse, they have shown the existence of two types of carriers. A large fraction of low mobility electrons is confined near the interface whereas a small fraction of high mobility electrons is more spread out into the SrTiO3. By correlating the Hall effect measurements with the critical temperatures as a function of the applied electric field, the researchers have shown that the high mobility electrons are responsible for the superconductivity.

References :

[1] Two-Dimensional Superconducting Phase in LaTiO3/SrTiO3 Heterostructures Induced by High-Mobility Carrier Doping. J. Biscaras, N. Bergeal, S. Hurand, C. Grossetête, A. Rastogi, R. C. Budhani, D. LeBoeuf, C. Proust et J. Lesueur, Phys. Rev. Lett. 108, 247004 (2012).

http://arxiv.org/abs/1112.2633

[2] Actualité de l’INP "Contrôler la supraconductivité entre deux isolants avec un champ électrique"