Experimental Studies of Intrinsic Nanoscale Localization for Low Lying Excitations in Solids

离散晶格中的非线性激发理论的一个最新进展是发现，完全周期晶格中的一些局域振动可以通过晶格的离散性稳定在大块晶体的表面或边缘。因为这些激发显示纳米尺度，并被预测将通过晶格移动，所以它们的实验产生和观察是最有意义的。为此，所提出的非线性自旋晶格系统的实验研究具有一定的优势，因为与晶体中的晶格振动相比，磁性材料中的自旋波的耗散较弱。因此，大幅度激发更容易获得，本项目的一个目标是从实验上检验反铁磁体中这种局域激发的物理性质。除了产生和探测外，探索本征局域模的传播和输运特性也很重要。根据磁激发的成功，还将探索与宏观和量子系统相关的本征局域化的实验研究。在周期晶格中的这种局部化只依赖于非线性和离散性的一般特征确保了在这一领域工作的研究生和本科生将接受跨越从纳米到宏观的各种长度尺度的非线性动力学的培训。这个实验计划旨在探索非线性周期物理系统动力学的基本简单性，其范围从原子晶格中的大幅度激发的研究到微型机电阵列中的研究。在这一新研究领域工作的研究生和本科生将接受凝聚态非线性动力学方面的培训，涉及所有具有重要技术意义的长度尺度。

9979483SieversA recent advance of the theory of nonlinear excitations in discrete lattices was the discovery that some localized vibrations in perfectly periodic lattices can be stabilized in bulk crystals, at their surfaces or at their edges by lattice discreteness. Because these excitations display nanoscale dimensions and are predicted to move through the lattice their experimental generation and observation is of paramount interest. To this end the proposed experimental study of nonlinear spin lattice systems has definite advantages because the dissipation of spin waves in magnetic materials is weak compared to that of lattice vibrations in crystals. Consequently, large amplitude excitations are more readily obtainable and one objective of this project is to examine experimentally the physical properties of such localized excitations in antiferromagnets. In addition to generation and detection it is also important to explore the propagation and transport properties of intrinsic localized modes. Depending on the successes found for magnetic excitations, experimental studies of intrinsic localization associated with macroscopic and quantum systems will also be explored. The general feature that such localization in periodic lattices depends only on nonlinearity plus discreteness ensures that graduate and undergraduate students working in this area will have training in nonlinear dynamics spanning a variety of length scales, ranging from the nano- to the macroscopic one.%%%This experimental program is directed at probing the underlying simplicity of the dynamics of nonlinear periodic physical systems, which range from studies of large amplitude excitations in atomic lattices to those in micro electrical mechanical arrays. Graduate and undergraduate students working in this new research area will have training in condensed matter nonlinear dynamics involving all the technologically important length scales.***