Local Electrostatic Modulation of Superconductivity in Nb-doped SrTiO₃ Films

Abstract

Format

This is a copy of the slides presented at the meeting but not formally written up for the volume.

Abstract

In this talk, the focus will be on recent experiments performed on superconducting doped SrTiO3 films using the ferroelectric field effect. Using thin single crystal films of Nb-doped SrTiO3, we have used the polarization field of ferroelectric Pb(Zr,Ti)O3 to electrostatically tune the electronic properties of Nb-doped SrTiO3. Atomic force microscopy was used to locally reverse the ferroelectric polarization, inducing large resistivity and carrier modulations, resulting in a clear shift in the superconducting critical temperature [1]. By poling sub-micron scale domains, the carrier density and the electronic properties of the superconducting channel were locally modified. Transport measurements reveal a steplike behavior in the current-voltage and resistance-magnetic field characteristics. This behavior, not observed in homogeneously poled samples, is ascribed to phase slip lines which are more easily generated in inhomogeneous superconductors. More generally, the technique developed should allow Josephson junctions, SQUIDS and superconducting circuits to be directly written in a Nb-doped SrTiO3 film using atomic force microscopy, an idea proposed in 1997 by C.H. Ahn et al. [2]. [1] K. Takahashi, D. Jaccard, M. Gabay, K. Shibuya, T. Ohnishi, M. Lippmaa, J.-M. Triscone, Nature 441,195 (2006). [2] C.H. Ahn, T. Tybell, L. Antognazza, K. Char, R.H. Hammond, M.R. Beasley, Ø. Fischer, and J.-M. Triscone. Science 276, 1100 (1997).