Nuclear Magnetic Resonance Investigations of Multi- Dimensionally Modulated Incommensurate Insulators

该项目需要核磁共振（NMR） 无公度系统的研究，即具有 完美的长程有序，但没有晶格周期性，因此 介于晶格和无序系统之间， 玻璃和生物系统。 无公度固体是 其特征在于至少有两个子晶格， 这不能用两个整数之比来描述。 这些 系统表现出一些新的现象，没有发现在完美的 晶体或无序系统：滑动质量密度波 不同于正常晶格中的晶格振动。 调制波的激励被称为相位子，并且可以被 通过核磁共振技术以独特的方式进行研究。 另外这些 调制波可以以类似于涡旋的方式被钉扎 超导体中的钉扎。 目前的研究将研究 一系列绝缘体中的钉扎和脱钉过程，包括 在1，2和3维的无公度晶格上的例子。 的 本建议书中所述的调查结果应 对于整个固态领域具有基本重要性 晶体中的“超流性”，因为调制波在一个 无公度固体可以被认为是固态超流体 其可以是带电的或不带电的。

This project entails nuclear magnetic resonance (NMR) investigations of incommensurate systems, i.e. solids which have perfect long range order but no lattice periodicity and are thus intermediate between crystal lattices and disordered systems like glasses and biological systems. Incommensurate solids are characterized by at least two sublattices the periodicities of which can not be described as the ratio of two integers. These systems exhibit a number of new phenomena not found in perfect crystals or disordered systems: an sliding mass density wave distinct from lattice vibrations in normal crystal lattices. Excitations of the modulation waves are known as phasons and can be studied in a unique fashion by NMR techniques. In addition, these modulation waves can become pinned in a manner similar to vortex pinning in superconductors. The current resaerch will study pinning and depinning processes in a range of insulators, including examples on incommensurate lattices in 1, 2 and 3 dimensions. The results of the investigations described in this proposal should be of basic importance for the whole field of solid-state "superfluidity" in crystals, since the modulation wave in an incommensurate solid may be thought of a solid-state superfluid which may be either charged or uncharged.