Studies of ferroelectric field effects in Pt/Pb(Zr/sub 0.5/Ti/sub 0.5/)O/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7/ heterostructures

Pt/Pb(Zr/sub 0.5/Ti/sub 0.5/)O/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7/ (Pt/PZT/YBCO) heterostructures were made by pulsed laser deposition on (100) SrTiO/sub 3/ or (100) LaSrGaO/sub 4/ substrates for studies of ferroelectric field effects in high-T/sub c/ superconducting thin films. X-ray diffraction data, including /spl Phi/ scans, indicated that the PZT layer grew with c-axis orientation epitaxially on top of the YBCO layers. Polarization measurements at room temperature and 77 K showed similar hysteretic loops in the PZT layer. The remanent polarization field can induce as many as 10/sup 14/ carriers/cm/sup 2/ in the bottom superconducting channel at the interface. Both c-axis and in-plane-aligned a-axis-oriented YBCO films, typically exhibiting zero resistance transition temperature of /spl sim/85 K, were used as superconducting channels. By polarizing the PZT film, a 2-5% change in both the channel resistance and the critical current at 77-85 K was obtained in /spl sim/100 nm thick films. Device operation at microsecond speeds was observed.