轻-重-空位模型中的相序动力学：不寻常的粗化动力学
Phase ordering kinetics in Light-Heavy-Vacancy model: unusual coarsening dynamics
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中文总结 AI 辅助
本研究通过一维晶格模型揭示轻-重-空位系统中不寻常的粗化动力学：早期畴解体而非合并，粒子粗化呈双幂律，景观粗化长度尺度短暂减小，并利用线性流体动力学解释行波机制。
中文摘要 AI 辅助
我们研究了一个一维晶格模型，该模型描述了一个耦合驱动系统，其中两种硬核粒子种类——'轻'粒子和'重'粒子——在波动的景观上运动。轻粒子倾向于沿景观局部高度梯度的方向向上移动，而重粒子倾向于向下移动。此外，这些粒子种类也对局部高度轮廓施加偏置。景观中未被占据或空缺的部分不受偏置影响，经历对称的高度波动。在先前的工作中，我们推导了该系统的相图，包含不同种类的有序和无序相。在有序相中，一种或两种粒子种类发生相分离，而景观形成大山丘或深谷。在这里，我们通过监测粒子和景观从初始无序状态发展出长程有序的过程来研究粗化。与传统的相序系统（其中粗化通过有序畴的形成和合并进行）不同，我们发现早期形成的畴在后期变得不可持续。这些早期畴不是合并，而是解体，新畴出现，最终在长时间极限下产生大规模有序结构，导致高度不寻常的粗化行为。对于粒子粗化，特征长度尺度在早期和晚期以两个截然不同的幂律指数增长。景观粗化则更为戏剧性，其长度尺度在短暂时间间隔内减小，而不是持续增加。在粗化阶段，景观的高度波动随时间表现出周期性振荡。利用线性流体动力学，我们解释这是由三种法向模式引起的，这些模式像行波一样在系统中传播。我们在平均场近似内计算了这些模式的传播速度。
英文摘要
We study a one dimensional lattice model of coupled driven system where two kinds of hardcore particle species, `light' and `heavy', move on a fluctuating landscape. Light particles prefer to move upward along the local height gradient of the landscape, and heavy particles prefer to move downhill. In addition, these particle species also exert bias on the local height profile. The unoccupied or vacant parts of the landscape experience no bias and undergo symmetric height fluctuations. In an earlier work, we had derived a phase diagram of the system consisting of different kinds of ordered and disordered phases. In the ordered phase, one or both particle species phase-separate, while the landscape forms a large hill or deep valley. Here we study coarsening by monitoring the development of long-range order in the particles and landscape from an initially disordered state. Unlike conventional phase-ordering systems, where coarsening proceeds through the formation and merger of ordered domains, here we find that domains formed at early times become unsustainable at later times. Instead of merging together, these early domains disintegrate and new domains emerge which finally give rise to large scale ordered structure in the long time limit, resulting a highly unusual coarsening behavior. For particle coarsening, the characteristic length scale grows with two distinctly different power law exponents at early and late times. The landscape coarsening is even more dramatic where the length scale decreases for brief time-intervals, instead of increasing continuously. The height fluctuations of the landscape shows periodic oscillations with time during the coarsening phase. Using linear hydrodynamics we explain that this is caused by three normal modes which move through the system like travelling waves. We calculate the propagation velocities of these modes within mean field approximation.
发表机构
- Department of Physics of Complex Systems, S. N. Bose National Centre for Basic Sciences（S. N. 玻色基础科学国家中心复杂物理系）
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