2008 年 29 巻 1 号 p. 31-35
We have performed local ferroelectric field effect experiments using an epitaxial heterostructure composed of ferroelectric Pb (Zr0.2Ti0.8)O3 and superconducting Nb doped SrTiO3, fabricated on an (100)SrTiO3 substrate by off-axis radio frequency magnetron sputtering and pulsed laser deposition. By switching the polarization field of the 50 nm thick Pb(Zr0.2Ti0.8)O3 layer, we induced a large change in resistivity and a shift of Tc in the 26 nm thick epitaxial Nb doped SrTiO3 layer. At 270 mK, superconducting on-off switch is realized. Ferroelectric domain array was poled in submicron scale by AFM (Atomic Force Microscope) tip to make a low Tc array in a high Tc superconducting path. A stepwise magnetoresistance was clearly observed in the array device around the Tc. This behavior suggests that 2D superconducting fluctuation induces phase slips and the low Tc array stabilizes them.