Relaxor ferroelectricity in strained epitaxial SrTiO3 thin films on DyScO3 substrates

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Abstract
The ferroelectric properties of 500 Å thick strained, epitaxial Sr Ti O 3 filmsgrown on Dy Sc O 3 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 ω are as narrow as 7 arc sec (0.002°). 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 μ 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.