Ordering Phenomena in Transition Metal Oxides

Two-dimensional superconductivity at the SrTiO₃/LaAlO₃ interface   

N. Reyren¹, S. Thiel², A. Caviglia¹, G. Hammerl², C. Richter², C. W. Schneider², T. Kopp², A.-S. Ruetschi¹, D. Jaccard¹, M. Gabay³, J. Mannhart², and J.-M. Triscone¹

¹DPMC, University of Geneva, 24 quai E.-Ansermet, 1211 Geneva 4, Switzerland.

² Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany.

³ Laboratoire de Physique des Solides, Bat 510, Université d'Orsay, 91405 ORSAY, Cedex, France.

At interfaces between complex oxides, electronic systems with unusual properties can be generated. As reported first by Ohtomo and Hwang [1], a highly mobile electron gas is formed at the interface between LaAlO₃ and SrTiO₃, two insulating dielectric perovskite oxides. It will be shown that the ground state of this system is superconducting [2]. The superconducting critical temperature is about 200mK and the superconducting thickness at most 4nm. The characteristics of the observed superconducting transitions are consistent with a superconducting sheet as thin as a few nm and a two dimensional Berezinskii-Kosterlitz-Thouless type behavior. As will be shown, the normal state and superconducting state properties can be dramatically tuned by an electric field.

References

[1] ''A high mobility electron gas at the LaAlO₃/SrTiO₃ heterointerface'', A. Ohtomo, H. Y. Hwang, Nature 427, 423 (2004). (corr. Nature 441, 120 (2006)).

[2] ''Superconducting interfaces between insulating oxides'', N. Reyren, et al., Science 317, 1196 (2007).