NMR Studies of the Mechanism of Superconductivity and Spin Fluctuations in High Tc and Related Layered Oxides

9623858 Imai掺杂铜氧化物的高温超导机制仍存在很大争议。最根本的困难在于，强的载流子-载流子关联效应不允许我们基于传统的智慧来描述T_c以上的正常金属状态。此外，未掺杂母体反铁磁性绝缘子的磁性和统计特性也很难理解。最近，麻省理工学院材料科学与工程中心设计和研制了一台新的核磁共振谱仪。该谱仪非常适合于研究载流子-载流子关联效应、金属-绝缘体相变、准二维量子自旋系统的磁性和统计性质、超导序参数的对称性以及相关现象。在拟议的项目中，将使用光谱仪研究各种高T_c氧化铜氧化物超导体和相关材料，特别是在高温下的核磁共振实验。核磁共振技术是研究固体物理和化学性质的一种理想的显微镜、无损探头。最近，麻省理工学院材料科学与工程中心开发了一台新的核磁共振波谱仪。该波谱仪允许人们进行独特的实验，以研究高温超导体和相关材料。最值得注意的是，高温下的困难实验可以按常规方式进行。在拟议的项目中，将利用核磁共振谱仪来了解铜氧化物超导体中高温超导的机制和相关现象。***

9623858 Imai The mechanism of high temperature superconductivity in doped copper oxides is still highly controversial. The fundamental difficulty lies in the fact that strong carrier-carrier correlation effects do not allow us to describe the normal metallic state above Tc based on the conventional wisdom. Moreover, the magnetism and statistical properties of the undoped parent antiferro- magnetic insulators are hard to understand. Recently, a new NMR (Nuclear Magnetic Resonance) spectrometer has been designed and developed at the Center for Materials Science and Engineering at M.I.T. The spectrometer is ideally suited to investigate carrier- carrier correlation effects, metal-insulator transitions, magnetic and statistical properties of quasi 2d quantum spin systems, the symmetry of the superconducting order parameter, and related phenomena. In the proposed project, a variety of high Tc copper oxide superconductors and related materials will be studied using the spectrometer with particular emphasis on NMR experiments at elevated temperatures. %%% The nuclear magnetic resonance technique is an ideal microscopic, nondestructive probe into the physical and chemical properties of solids. Recently, a new NMR spectrometer has been developed at the Center for Materials Science and Engineering at M.I.T. The spectrometer allows one to conduct unique experiments to investigate high temperature superconductors and related materials. Most notably, difficult experiments at elevated temperatures can be conducted in a routine manner. In the proposed project, the NMR spectrometer will be utilized to understand the mechanism of high temperature superconductivity and related phenomena in copper oxide superconductors. ***