Scott John J R, Casals Blai, Luo King-Fa, Haq Atta, Mariotti Davide, Salje Ekhard K H, Arredondo Miryam
School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN Northern Ireland, UK.
Department of Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ England, UK.
Sci Rep. 2022 Sep 1;12(1):14818. doi: 10.1038/s41598-022-18390-7.
Ferroic domain dynamics, as a function of external stimuli, can be collectively described as scale-invariant avalanches characterised by a critical exponent that are sensitive to the complexity of the domain microstructure. The understanding and manipulation of these avalanches lies at the heart of developing novel applications such as neuromorphic computing. Here we combine in situ heating optical observations and mean-field analysis to investigate the collective domain behaviour in pure-ferroelastic lanthanum aluminate (LaAlO[Formula: see text]) as a function of aspect ratio, the ratio of sample length to width, where the movement of the domains is predominantly driven by thermal stresses via thermal expansion/contraction during heat cycling. Our observations demonstrate that the aspect ratio induces (1) distinctive domain microstructures at room temperature, (2) a deviation of dynamical behaviour at high temperatures and (3) critical exponent mixing in the higher aspect ratio samples that accompanies this behaviour. While the critical exponents of each aspect ratio fall within mean-field predicted values, we highlight the effect that the aspect ratio has in inducing exponent mixing. Hence, furthering our understanding towards tuning and controlling avalanches which is crucial for fundamental and applied research.
铁电畴动力学作为外部刺激的函数，可以被统一描述为具有临界指数的尺度不变雪崩，这些雪崩对畴微结构的复杂性敏感。对这些雪崩的理解和操控是开发诸如神经形态计算等新型应用的核心。在此，我们结合原位加热光学观测和平均场分析，研究纯铁弹性铝酸镧（LaAlO₃）中畴的集体行为与长宽比（样品长度与宽度之比）的函数关系，其中在热循环过程中，畴的运动主要由热膨胀/收缩产生的热应力驱动。我们的观测结果表明，长宽比会导致（1）室温下独特的畴微结构，（2）高温下动力学行为的偏差，以及（3）伴随这种行为的高长宽比样品中的临界指数混合。虽然每个长宽比的临界指数都落在平均场预测值范围内，但我们强调了长宽比在诱导指数混合方面的作用。因此，加深了我们对调节和控制雪崩的理解，这对基础研究和应用研究至关重要。
