Nuclear Magnetic Resonance Investigations of Multi- Dimensionally Modulated Incommensurate Insulators

多维调制不通约绝缘体的核磁共振研究

• 批准号: 9024196
• 负责人: David Ailion
• 金额: $ 24.5万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-07-01 至 1995-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9024196&HistoricalAwards=false
• 关键词: Nuclear; Magnetic; Resonance; Investigations; Multi

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.

该项目需要对不通约系统进行核磁共振（NMR）研究，即具有完美长程有序但没有晶格周期性的固体，因此介于晶格和无序系统（如玻璃和生物系统）之间。 不相称固体的特征在于至少两个子晶格，其周期性不能描述为两个整数的比率。 这些系统表现出许多在完美晶体或无序系统中未发现的新现象：与正常晶格中的晶格振动不同的滑动质量密度波。 调制波的激发被称为相子，可以通过核磁共振技术以独特的方式进行研究。 此外，这些调制波可以以类似于超导体中涡旋钉扎的方式被钉扎。 当前的研究将研究一系列绝缘体中的钉扎和脱钉过程，包括一维、二维和三维不相称晶格的示例。 该提案中描述的研究结果对于晶体中的固态“超流性”的整个领域应该具有基本重要性，因为不相称固体中的调制波可以被认为是可以带电或不带电的固态超流体。