Ferroelectric BaTiO3 thin films grown on NdScO3 substrates show low misfit strain (~0.05 domain structure near 50 C. We utilize X-ray photon correlation spectroscopy (XPCS) to characterize the thermal fluctuations in such a low-strain system providing a direct comparison between second and first order phase transformations. The a/b to a/c domain transformation is accompanied by a decrease in correlation timescales, and an increase in intensity and correlation lengthscales. Surprisingly, domain fluctuations up to 25 C above the transformation are observed concomitant with growth of a/c domains and presence of a/b domains. After a small window of stability, as the Curie temperature is approached, a/c domain fluctuations are again observed albeit slower, potentially due to structural transformation associated with a first order transformation. The observed time evolution and reconfiguration of domain pattern highlight the role played by phase separation and strain in altering fluctuations timescales in ferroelectric thin films.

中文翻译：

---

铁电低应变BaTiO3薄膜中的畴涨落

在NdScO3衬底上生长的铁电BaTiO3薄膜显示出低的失配应变（在50°C附近具有〜0.05的畴结构）。我们利用X射线光子相关光谱（XPCS）来表征这种低应变系统中的热涨落，从而可以直接比较从a / b到a / c的域转换，伴随着相关时间尺度的减小，强度和相关长度尺度的增大，令人惊讶的是，观察到在该变换之上高达25 C的域波动伴随着生长在一个较小的稳定性窗口之后，随着接近居里温度，尽管可能较慢，这可能是由于与一阶转换相关的结构转换，但仍观察到a / c区域波动，尽管速度较慢。观察到的时间演化和畴图案的重新配置突出了相分离和应变在改变铁电薄膜的波动时标中所起的作用。