Multilayer ferroelectric-high T/sub c/ structures with poled ferroelectric layers

We have observed shifts of from 0.5 to -6/spl deg/K in the T/sub C(ONSET/) of YBa/sub 2/Cu/sub 3/O/sub 7-x/(123) in laser ablated thin film 123-BaTiO/sub 3/ multilayer structures on (100) oriented LaAlO/sub 3/ upon poling of the BaTiO/sub 3/ with a positive potential. Poling was carried out at between 120 and 150/spl deg/C in air with an applied field of about 10/sup 5/ V/cm after which a positive shift in the T/sub C(ONSET/) of the 123 by an amount of approximately 1/spl deg/K was observed. Samples were also poled at room temperature (20/spl deg/C) with an applied field of 10/sup 6/ V/cm (2-6/spl deg/K shift observed depending on T/sub c/ (R=0)). Negative potentials showed no apparent shift in T/sub C(ONSET/). A dc-poling with no applied field at 150/spl deg/C for 10-30 minutes in air was observed to restore the R vs. T curve to its original, unpoled, state. Details of the deposition parameters, structures and the mast recently obtained results will be presented possible explanations for the effect will also be discussed.<>