Nanosize ferroelectric oxide -: tracking down the superparaelectric limit

Free ferroelectric nanoparticles in the order of 10 nm undergo a size driven phase transition into a paraelectric phase. However, in all applications, especially in ferroelectric random access memories, ferroelectric nanograins are integrated into a circuit. They are therefore exposed to new electromechanical boundary conditions e.g. substrate strain and screening of the depolarization field in the electrodes. Carefully adapted to the respective material, some of the extrinsic effects can be used to stabilize ferroelectricity and to shrink the ultimate size. The system performance is very sensitive to the fabrication and processing procedures.