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

9979483Sievers9979483Sievers9979483Sievers9979483Sievers9979483Sievers9979483Sievers99979483Sievers99979483Sievers99979483Sievers99979483Sievers99979483Sievers999979483Sievers9997979483Sievers99979483Sievers999979483Sievers999979483Sievers999979483Sievers99979483Sievers9997979483Sievers999797979483Sievers9979797979483Sievers97979797 由于这些激发显示纳米尺度的尺寸，并预计通过晶格移动，其实验产生和观察是最重要的兴趣。 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，因为磁性材料中的自旋波的耗散与晶体中的晶格振动相比是弱的。因此，大振幅的激发是更容易获得的，这个项目的一个目标是实验研究反铁磁体中的这种局部激发的物理性质。 除了产生和检测，探索本征局域模的传播和输运特性也很重要。 根据磁激发的成功发现，与宏观和量子系统相关的内在本地化的实验研究也将进行探索。 一般的特点，这种定位在周期性晶格只取决于非线性加上离散性，确保研究生和本科生在这一领域工作将有培训的非线性动力学跨越各种长度尺度，从纳米到宏观。这个实验计划是针对探索非线性周期性物理系统的动力学的基本简单性，其范围从原子晶格中的大振幅激发的研究到微机电阵列中的研究。 在这个新的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的培训，涉及所有技术上重要的长度尺度。

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.***