Nature441, 195-198 (11 May 2006) | doi:10.1038/nature04731; Received 11 October 2005; Accepted 16 March 2006
Local switching of two-dimensional superconductivity using the ferroelectric field effect
K. S. Takahashi1, M. Gabay2, D. Jaccard1, K. Shibuya3, T. Ohnishi3, M. Lippmaa3 and J.-M. Triscone1
Correlated oxides display a variety of extraordinary physical properties including high-temperature superconductivity1 and colossal magnetoresistance2. In these materials, strong electronic correlations often lead to competing ground states that are sensitive to many parameters—in particular the doping level—so that complex phase diagrams are observed. A flexible way to explore the role of doping is to tune the electron or hole concentration with electric fields, as is done in standard semiconductor field effect transistors3. Here we demonstrate a model oxide system based on high-quality heterostructures in which the ferroelectric field effect approach can be studied. We use a single-crystal film of the perovskite superconductor Nb-doped SrTiO3 as the superconducting channel and ferroelectric Pb(Zr,Ti)O3 as the gate oxide. Atomic force microscopy is used to locally reverse the ferroelectric polarization, thus inducing large resistivity and carrier modulations, resulting in a clear shift in the superconducting critical temperature. Field-induced switching from the normal state to the (zero resistance) superconducting state was achieved at a well-defined temperature. This unique system could lead to a field of research in which devices are realized by locally defining in the same material superconducting and normal regions with 'perfect' interfaces, the interface being purely electronic. Using this approach, one could potentially design one-dimensional superconducting wires, superconducting rings and junctions, superconducting quantum interference devices (SQUIDs) or arrays of pinning centres.
DPMC, University of Geneva, 24 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland
Laboratoire de Physique des Solides, Université de Paris-Sud, 91405 Orsay, France
Institute for Solid State Physics, University of Tokyo, Chiba 277-8581, Japan