Relaxor ferroelectricity in strained epitaxial SrTiO3 thin films on DyScO3 substrates

The ferroelectric properties of 500 A thick strained, epitaxial SrTiO3 films grown on DyScO3 substrates by reactive molecular-beam epitaxy are reported. Despite the near 1% biaxial tensile strain, the x-ray rocking curve full widths at half maximum in omega are as narrow as 7 arc sec (0.002 degrees). The films show a frequency-dependent permittivity maximum near 250 K that is well fit by the Vogel-Fulcher equation. A clear polarization hysteresis is observed below the permittivity maximum, with an in-plane remanent polarization of 10 mu C/cm(2) at 77 K. The high T-max is consistent with the biaxial tensile strain state, while the superimposed relaxor behavior is likely due to defects.(c) 2006 American Institute of Physics.