Salmani-Rezaie Salva, Ahadi Kaveh, Strickland William M, Stemmer Susanne
Materials Department, University of California, Santa Barbara, California 93106-5050, USA.
Phys Rev Lett. 2020 Aug 21;125(8):087601. doi: 10.1103/PhysRevLett.125.087601.
SrTiO_{3} is an incipient ferroelectric that is believed to exhibit a prototype displacive, soft mode ferroelectric transition when subjected to mechanical stress or alloying. We use high-angle annular dark-field imaging in scanning transmission electron microscopy to reveal local polar regions in the room-temperature, paraelectric phase of strained SrTiO_{3} films, which undergo a ferroelectric transition at low temperatures. These films contain nanometer-sized domains in which the Ti columns are displaced. In contrast, these nanodomains are absent in unstrained films, which do not become ferroelectric. The results show that the ferroelectric transition of strained SrTiO_{3} is an order-disorder transition. We discuss the impact of the results on the nature of the ferroelectric transition of SrTiO_{3}.
钛酸锶（SrTiO₃）是一种准铁电体，据信在受到机械应力或合金化作用时会呈现出典型的位移型软模铁电转变。我们利用扫描透射电子显微镜中的高角度环形暗场成像，揭示了应变钛酸锶薄膜在室温顺电相中的局部极化区域，这些薄膜在低温下会发生铁电转变。这些薄膜包含纳米尺寸的区域，其中钛柱发生了位移。相比之下，未应变的薄膜中不存在这些纳米畴，且不会变成铁电体。结果表明，应变钛酸锶的铁电转变是一种有序-无序转变。我们讨论了这些结果对钛酸锶铁电转变本质的影响。
