Dynamics of Disordered Non-Equilibrium Systems: Hysteresis, Noise, and Domain Wall Dynamics in Systems Ranging from Magnets to Earthquakes

许多系统“破裂”；当被缓慢推动时，它们会以大小和持续时间分布广泛的离散事件做出反应。地球对缓慢的构造运动作出反应，产生大小不等的地震，从微小的震动到毁灭性的九级地震。同样，在缓慢变化的外部磁场中，磁带会产生一系列的跳跃（巴克豪森噪声）——从微观到宏观大小的重新定向磁畴的雪崩。在过去的几年中，在驱动的、无序的、非线性的动力系统中，尺度不变的、通常是普遍的行为的模型和理论的发展取得了迅速的进展。这个理论项目将根据实验结果仔细测试其中的一些模型，为未来的实验提取普遍的预测，在必要时扩展模型以充分描述实验，并探索相应的普遍性类的大小。所采用的方法范围从数值模拟到尺度理论，并借鉴了从流体力学到动力学和无序系统理论的思想。知识价值：巴克豪森噪声是研究迟滞系统中集体“噼啪”噪声的理想实验实例系统。相对而言，它易于进行实验，也具有商业利益，就像无损检测一样。非平衡零温度随机场伊辛模型（RFIM）和最近的变种（应用远远超出磁系统）已经非常成功地模拟了从巴克豪森噪声测量中获得的大量不同材料的通用标度指数。在有限场扫描速率下，在模型中加入温度波动，将探索从远离平衡到接近平衡的整个实验相关交叉状态，并与最近在磁性和铁电系统中的实验进行比较。将详细比较相应的平衡和非平衡普适性类，以回答与实验和应用相关的长期问题。更广泛的影响是双重的。参与该项目的学生将获得广泛的技能，并学会与理论家、实验家和可能的工业代表一起工作。除了具有重要的基础意义外，该研究结果还具有技术应用前景。%%%许多系统“崩溃”；当被缓慢推动时，它们会以大小和持续时间分布广泛的离散事件做出反应。地球对缓慢的构造运动作出反应，产生大小不等的地震，从微小的震动到毁灭性的九级地震。同样，在缓慢变化的外部磁场中，磁带会产生一系列的跳跃（巴克豪森噪声）——从微观到宏观大小的重新定向磁畴的雪崩。在过去的几年中，在驱动的、无序的、非线性的动力系统中，尺度不变的、通常是普遍的行为的模型和理论的发展取得了迅速的进展。这个理论项目将根据实验结果仔细测试其中的一些模型，为未来的实验提取普遍的预测，在必要时扩展模型以充分描述实验，并探索相应的普遍性类的大小。所采用的方法范围从数值模拟到尺度理论，并借鉴了从流体力学到动力学和无序系统理论的思想

Many systems "crackle"; when pushed slowly they respond with discrete events in a broad distribution of sizes and durations. The earth responds to slow tectonic motion with quakes ranging in size from tiny tremors to devastating multitude-nine quakes. Similarly, a magnetic tape in a slowly changing external magnetic field magnetizes in a series of jumps (Barkhausen noise) - avalanches of reorienting magnetic domains that range from microscopic to macroscopic in size.In the past few years there has been rapid progress in developing models and theories of scale-invariant, often-universal behavior in driven, disordered, nonlinear, dynamical systems. This theoretical project will carefully test some of these models against experimental results, extract universal predictions for future experiments, extend the models if necessary to adequately describe experiments, and explore the size of the corresponding universality classes. The methods employed range from numerical simulations to scaling theories, and draw on ideas ranging from hydrodynamics to dynamical and disordered systems theory.Intellectual merit: Barkhausen noise serves as an ideal experimental example system for studying collective "crackling" noise in hysteretic systems. It is relatively accessible to experiments and is also of commercial interest, as for non-destructive testing. The non-equilibrium zero temperature random field Ising model (RFIM) and recent variants (with applications far beyond magnetic systems) have been extraordinarily successful in modeling universal scaling exponents obtained from Barkhausen noise measurements in a large class of different materials. Adding temperature fluctuations to the model at finite field sweep rate, the entire experimentally relevant crossover regime from far-from equilibrium to close-to equilibrium will be explored and compared to recent experiments in magnetic and ferroelectric systems. The corresponding equilibrium and non-equilibrium universality classes will be compared in detail, to answer long-standing questions relevant to both experiments and applications.Broader impact is two-fold. Students involved with the project will gain a broad range of skills and learn to work with groups of theorists, experimentalists and possibly industrial representatives. Besides being of great fundamental importance, the results of this research hold promise of technological applications.%%%Many systems "crackle"; when pushed slowly they respond with discrete events in a broad distribution of sizes and durations. The earth responds to slow tectonic motion with quakes ranging in size from tiny tremors to devastating multitude-nine quakes. Similarly, a magnetic tape in a slowly changing external magnetic field magnetizes in a series of jumps (Barkhausen noise) - avalanches of reorienting magnetic domains that range from microscopic to macroscopic in size.In the past few years there has been rapid progress in developing models and theories of scale-invariant, often-universal behavior in driven, disordered, nonlinear, dynamical systems. This theoretical project will carefully test some of these models against experimental results, extract universal predictions for future experiments, extend the models if necessary to adequately describe experiments, and explore the size of the corresponding universality classes. The methods employed range from numerical simulations to scaling theories, and draw on ideas ranging from hydrodynamics to dynamical and disordered systems theory.***