U.S.-Austria Cooperative Research on the Nonlinear AC Dynamics of Collective Modes

该奖项支持加州大学洛杉矶分校的乔治格鲁纳教授和 研究生与Karlheinz Seeger博士合作， 路德维希玻尔兹曼固态研究所（Ludwig Boltzmann Institute for Solid State） 物理学和奥地利维也纳大学。 他们分享一个 感兴趣的是电荷密度的非线性交流响应 波（CDW）基态。 通过结合实验 两个机构现有的技术，他们将 探索一系列非线性频率依赖现象， 固体 他们将扩大他们以前的合作， 低温（或II型）CDW动力学， 它的性质与高浓度的 温度动力学 此外，他们将开始新的 高温非线性交流响应的研究 超导体，与实验进行的功能 温度和外部磁场的影响 他们有 先前研究的小振幅交流响应的高 微波和毫米波温度超导体 光谱范围 这项工作将继续下去， 解释非线性响应的关键。 奥地利 科学家们将来到加州大学洛杉矶分校， (low现场）交流响应实验对各种单 晶体和薄膜样品。 同样的标本 然后在路德维希实验室研究交流谐波混频 维也纳的玻尔兹曼研究所。 高温超导性是研究的重点， 当前兴趣 电荷密度波的研究也是一个 固体物理学中非常活跃的领域。 对于两个收费 密度波和超导体在涡旋状态， 某些响应基本上由晶格决定 违规行为。 因此，存在显著的变化， 样本到样本，相同的关键响应集必须 在每个样本上进行测量。 合作的美国和 奥地利研究小组带来了一个独特的组合， 有能力解决这些问题。 互补 实验方法和测量设备在两个 实验室允许全面调查线性 和非线性响应现象 波谱范围 小振幅交流响应可以是 在加州大学洛杉矶分校监测了大量的光谱范围，而 非线性交流响应是在维也纳测量的， 频率.

This award supports Professor George Gruner of UCLA and a graduate student to collaborate with Dr. Karlheinz Seeger and other of the Ludwig Boltzmann Institute for Solid State Physics and the University of Vienna, Austria. They share an interest in the nonlinear ac response of the charge density wave (CDW) ground state. By combining the experimental techniques available at the two institutions, they will explore a range of nonlinear frequency dependent phenomena of solids. They will extend their previous collaboration on CDW's to the low temperature (or type II) CDW dynamics, which has properties fundamentally different from the high temperature dynamics. In addition, they will begin new studies of the nonlinear ac response of high temperature superconductors, with experiments conducted as the function of both temperature and external magnetic fields. They have previously studied the small amplitude ac response of the high temperature superconductors in the micro- and millimeter wave spectral range. This work, which will be continued, is essential in interpreting nonlinear response. Austrian scientists will come to UCLA to conduct the small amplitude (low field) ac response experiments on various single crystal and thin film specimens. The same specimens will then be investigated for ac harmonic mixing at the Ludwig Boltzmann Institute in Vienna. High temperature superconductivity is the focus of very great current interest. Charge density wave research is also a very active area in solid state physics. For both charge density waves and the superconductors in the vortex state, certain responses are fundamentally determined by lattice irregularities. Thus there are significant variations from specimen to specimen, and the same key set of responses must be measured on each specimen. The collaborating U.S. and Austrian research groups bring a unique combination of capabilities to bear on these problems. Complementary experimental methods and measurement facilities at the two laboratories allow the comprehensive investigation of linear and nonlinear response phenomena in the micro-and millimeter wave spectral range. The small amplitude ac response can be monitored at UCLA over a substantial spectral range, while the nonlinear ac response is measured at Vienna at selected frequency.