Dynamics of Extended Non-Equilibrium Systems: Hysteresis, Electromigration, and Defect Chaos

9419506 Sethna在长尺度上出现的集体行为将在三个系统中进行探索。 首先，研究人员将研究与某些磁滞回线相关的突发的无序诱导成核，并研究其结果在磁记录中的创新应用。 其次，将分析研究大的，移动的空洞的动力学，并使用散装铝和铜的真实模拟。 这项工作将有助于理解高电流密度的微加工器件中存在的故障。 第三，在二维系统中的混沌状态描述的偏微分方程的拓扑缺陷在一个混乱的，动荡的方式进行了研究。 更一般的粗粒化方法将用于研究相变和边界的影响，并了解这些系统中的噪声的性质。 对于许多系统，即使单个粒子相互作用的基本物理是复杂的，但在大尺度上往往可以找到相当简单的定律。我们将从理论上研究三个这样的系统的例子，这些系统被迫远离平衡。 首先，某些系统（如磁铁）的行为取决于参数（如外部磁场）是否增加或减少。 这些系统将被调查，这些结果将被应用到磁记录。 其次，将使用方程和计算机模拟来研究铝和铜等材料中的空隙（气穴）的运动，目的是更好地了解高电流流过微加工器件的故障。 第三，混沌噪声和缺陷的行为将在某些类别的二维系统中进行研究，例如被迫流动的流体和心肌壁。 ***

9419506 Sethna Collective behavior emerging on long length scales will be explored in three systems. First, the investigator will study disorder-induced nucleation of bursts associated with certain hysteresis loops and investigate innovative applications to magnetic recording which result. Second, the dynamics of large, mobile voids will be studied analytically and using realistic simulations of bulk aluminum and copper. This work will help understand failure present in microfabricated devices with high current densities. Third, chaotic states in two-dimensional systems described by partial differential equations whose topological defects move in a chaotic, turbulent manner will be studied. More general coarse-graining methods will be used to investigate phase transitions and the effects of boundaries, and to understand the nature of noise in these systems. %%% For many systems, even though the underlying physics of the interactions of the individual particles is complex, on a large scale rather simple laws can often be found. Three examples of such systems that are forced to be far from equilibrium will be investigated theoretically. First, certain systems, such as magnets, behave differently depending on whether a parameter (such as an external magnetic field) is increased or decreased. Such systems will be investigated and these results will be applied to magnetic recording. Second, the movement of voids (pockets of air) in materials such as aluminum and copper will be investigated using equations and computer simulations, with a goal to better understand failure in microfabricated devices with high currents flowing through them. Third, the behavior of chaotic noise and defects will be investigated in certain classes of two-dimensional systems, such as fluids that are forced to flow and heart muscle walls. ***