Studies of ferroelectric field effects in Pt/Pb(Zr0. 5Ti0. 5)O3/YBa2Cu3O7 heterostructures

Pt/Pb(Zr0. 5Ti0. 5)O3/YBa2Cu3O7 (Pt/PZT/YBCO) heterostructures were made by pulsed laser deposition on (lOO)SrTiOj or (100) LaSrGaO4 substrates for studies of ferroelectric field effects in high-Tc superconducting thin films. X-ray diffraction data including <t> 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 rémanent polarization field can induce as many as 10 carriers/cm 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 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 100 nm thick films. Device operation at microsecond speeds was observed. © 1997 IEEE.