Multilayer ferroelectric-high Tc structures with poled ferroelectric layers

摘要

We have observed shifts of from 0.5 to -6°K in the TC(ONSET) of YBa2Cu3O7-x(123) in laser ablated thin film 123-BaTiO3 multilayer structures on (100) oriented LaAlO3 upon poling of the BaTiO3 with a positive potential. Poling was carried out at between 120 and 150°C in air with an applied field of about 105 V/cm after which a positive shift in the TC(ONSET) of the 123 by an amount of approximately 1°K was observed. Samples were also poled at room temperature (20°C) with an applied field of 106 V/cm (2-6°K shift observed depending on Tc (R=0)). Negative potentials showed no apparent shift in TC(ONSET). A dc-poling with no applied field at 150°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.