Nanoscale switching and domain structure of ferroelectric BaBi4Ti4O15 thin films

Ferroelectric domain structures of epitaxial BaBi4Ti4O15 (BBiT) thin films with different orientations have been imaged for the first time at the nanometer scale. Using the piezoresponse mode of scanning force microscopy it was demonstrated that the spontaneous polarization of BBiT has no component along the c-axis of the unit cell. Local piezoelectric hysteresis loops from non c-oriented grains with lateral sizes of 300 to 500 nm were recorded. The saturation values of the piezoelectric constant perpendicular to the c-axis are comparable to those measured macroscopically. A distinct ferroelectric behavior was still found in grains as small as 300 nm in lateral size.