Fatigue anisotropy in pulsed laser deposited PYbN-PT thin films

Heterostructures consisting of a (100) LaAlO3 (LAO) or (111) SrTiO3 (STO) s ubstrate, a SrRuO3 (SRO) metallic oxide bottom electrode, and a (1-x) Pb[Yb 1/2Nb1/2]O-3 - x PbTiO3 (PYbN-PT, x similar to0.5 or 0.6) ferroelectric thi n film were grown by the pulsed laser deposition process. The films were pe rovskite structured, with orientations that ranged from highly < 001 > (pc) -oriented PYbN-PT/SRO/LAO to highly < 111 > (pc)-oriented PYbN-PT/SRO/STO m ultilayer systems. According to the crystal orientation, the ferroelectric and fatigue characteristics of such as-grown planar capacitors vary signifi cantly. In particular, < 001 > (pc)-heteroepitaxial thin films result in fa tigue-free capacitors up td 10(11) cycles while < 111 > (pc)-oriented heter ostructures exhibit a marked degradation of the switchable polarization by ac voltage cycling. These data agree with recent findings of fatigue anisot ropy in relaxer ferroelectric-PbTiO3 single crystals. This orientation depe ndence may result from differences in the domain configuration and switchin g process.