Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom.
Phys Rev Lett. 2018 Dec 7;121(23):235701. doi: 10.1103/PhysRevLett.121.235701.
Polar and highly mobile domain walls in SrTiO_{3} move under electric and elastic fields. Two vastly different timescales dominate their dynamical behavior. The previously observed fast changes lead to anomalies near 40 K where the elastic moduli soften and the polarity of the walls becomes strong. Keeping the sample under isothermal conditions leads to a new and unexpected phenomenon: The softening vanishes over timescales of days while the piezoelectricity of the sample remains unchanged. The hardening follows glass dynamics below an onset at T^{*}≈40 K. The timescale of the hardening is strongly temperature dependent and can be followed experimentally down to 34 K when the relaxation is not completed within two days. The relaxation time of a stretched exponential decay increases exponentially with the decreasing temperature. This relaxation process follows similar dynamics after zero-field cooling and after applying or removing an electric field. The sluggish behavior is attributed to collective interactions of domain patterns following overdamped glass dynamics rather than ballistic dynamics.
SrTiO3 中的极性和高度迁移的畴壁在电场和弹性场下移动。两种截然不同的时间尺度主导着它们的动力学行为。先前观察到的快速变化导致弹性模量软化和壁的极性变强的异常现象，其温度在 40K 附近。在等温条件下保持样品，会导致一个新的、意想不到的现象：在几天的时间内，软化现象消失，而样品的压电性能保持不变。在 T*≈40K 以下，硬化遵循玻璃动力学。硬化的时间尺度强烈依赖于温度，可以通过实验跟踪到 34K，此时在两天内松弛未完成。拉伸指数衰减的弛豫时间随温度的降低呈指数增加。这种弛豫过程在零场冷却后以及施加或移除电场后遵循相似的动力学。这种缓慢的行为归因于畴模式的集体相互作用，遵循过阻尼玻璃动力学，而不是弹道动力学。
