Polarization rotation transitions in anisotropically strained SrTiO3 thin films

Commensurately strained epitaxial SrTiO3 thin films on a GdScO3 substrate with anisotropic in-plane tensile strains of 1.46% and 1.59% were grown. By using optical second harmonic generation and polarization measurements, a ferroelectric transition from a tetragonal 4/mmm phase to a ferroelectric mm2 phase at similar to 400 K and an antiferrodistortive transition to a multiferroic phase at 150-175 K are observed, which are in agreement with thermodynamic calculations. In addition, a series of polarization rotation transitions between < 100 >(p) to < 100 >(p) (0 < l < 1) is observed in the 4-400 K temperature range. (c) 2008 American Institute of Physics.