Experimental Studies of Nanoscale Energy Localization in Periodic Condensed Matter Systems

这个个人研究者奖支持一个研究计划，专注于凝聚态物理学中非线性纳米尺度定位现象和离散模式形成的实验研究。在纳米尺度区域上产生这种固有能量局域化的一种方法是利用特定大振幅非线性平面波激发的调制不稳定性。为了更好地理解晶体中从平面波不稳定性到纳米级能量局域化的途径，将进行三种不同类型的实验：（a）一维微机械阵列中的本征局域模（ILM）将使研究单色能量局域化现象的长时间产生成为可能。(b)本征局域自旋波模式在经典的一维类反铁磁晶体将进行研究，试图观察新预测的本地化自旋翻转，这代表了一个更本地化和更大的能量激发比ILM。(c)量子反铁磁体和软模顺电晶体中的固有纳米级能量局域化将使用杰斐逊实验室产生的高强度宽带太赫兹辐射进行研究。在进行非线性实验加上数值模拟研究生和本科生将开发在这个发展中的跨学科领域的专业知识。 非线性和格点离散性在物理学的许多分支中都扮演着重要的角色。凝聚态物理学的传统方法是将这两个项目分开处理。最近人们预测并认识到，在强非线性离散系统中会出现全新的动力学现象。例如，固体中的大振幅长波长振动可以快速级联并在原子尺度上局部化，振动振幅大幅增加。由此产生的离散的纳米级图案在晶体中的预测，以引起不同的物理状态。这项实验研究计划探索了这些新现象。非线性能量局部化行为的科学活动的快速增长表明，这些效应可能在许多领域发挥作用，例如摩擦和裂纹扩展。还有一些发展中的领域涉及更大的长度尺度，如光开关，非线性光子晶体波导，周期性电约瑟夫森结阵列，微机电硅系统，并在最大的规模，在高能加速器中的多束模式的本地化。 从事该项目的研究生和本科生将接受凝聚态系统非线性动力学方面的培训，这些系统涉及技术上重要的长度尺度。

This individual investigator award supports a research program focused on the experimental investigation of nonlinear nanoscale localization phenomena and discrete pattern formation in condensed matter physics. One way to produce such intrinsic energy localization over a nanoscale region is by making use of the modulational instability of specific large amplitude nonlinear plane wave excitations. To better understand the pathways from plane wave instability to nanoscale energy localization in crystals, three different classes of experiments will be carried out: (a) Intrinsic localized modes (ILMs) in 1D micromechanical arrays will make possible the study of the long time production of monochromatic energy localization phenomena. (b) Intrinsic localized spin wave modes in classical 1D-like antiferromagnetic crystals will be studied in an attempt to observe the newly predicted localized spin flop, which represents a more localized and larger energy excitation than does an ILM. (c) Intrinsic nanoscale energy localization in quantum antiferromagnets and also in soft mode paraelectric crystals will be investigated using high-intensity broadband THz radiation produced at the Jefferson Laboratory. In carrying out nonlinear experiments coupled with numerical simulations both graduate and undergraduate students will develop expertise in this developing interdisciplinary field. Both nonlinearity and lattice discreteness have played important roles in many branches of physics. The traditional approach in condensed matter physics has been to treat these two items separately. Recently it has been predicted and realized that completely new kinds of dynamical phenomena occur in strongly nonlinear discrete systems. For example, large amplitude long wavelength vibrations in a solid can rapidly cascade down and localize at the atomic scale with a large increase in the vibrational amplitude. The resulting discrete nanoscale patterns in the crystal are predicted to give rise to different physical states. This experimental research program explores such new phenomena. The rapid growth of scientific activity in nonlinear energy localization behavior has shown there are a variety of areas where these effects may play a role, such as friction, and crack propagation. Still other developing areas involve somewhat larger length scales such as optical switches, nonlinear photonic crystal waveguides, periodic electrical Josephson junction arrays, micro-electrical-mechanical silicon systems, and, at the largest scale, the localization within multibunch modes in high energy accelerators. Graduate and undergraduate students working on this project will receive training in nonlinear dynamics in condensed matter systems involving technologically important length scales.