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Condensed Matter Research using Intense Spallation Neutrons

使用强散裂中子进行凝聚态物质研究

基本信息

批准号：
04044160
负责人：
IKEDA Hironobu
金额：
$ 18.82万
依托单位：
National Laboratory for High Energy Physics
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

The Japan-UK Collaboration in Neutron Scattering is a consequence of an Agreement between the Japanese National Laboratory for High Energy Physics (KEK) and UK Science and Engineering Research Council (SERC) established in 1986 to promote scientific collaboration and interchange between Japanese and UK scientists in the field of pulsed neutron scattering It has resulted in the construction of the MARI spectrometer at the ISIS Facility and has given formal accsess to the scientific program at ISIS for Japanese scientists.The scientific achievements of the Japan-UK Collaboration in the year of 1994 are as follows.Highlights of the work in the area of high-Tc superconductors and related materials include the measurements on MARI of the dynamical structure factor S (Q,epsilon) of examples of the high-Tc cuprates, La_<1.85>Sr_<0.15>CuO_4. These experiments revealed anomalous high-energy magnetic fluctuations extending up to 300 meV which are quite different from YBa_2Cu_3O_7.Quantum effects on one-dimensional Heisenberg antiferromagnet with S=3/2, CsVCl_3, were investigated. Using MARI they were able to determine the full dispersion of the magnetic excitations, with zone boundary energies of 75 meV.One of the key results of these measurements is that there is nogap at the zone center as was found in the integer spin case.Hydrogen plays a fundamental role in the properties of many solid materials. Neutrons can gain information on its position in the structure and its dynamical behavior. Quantum theory is necessary to account for the latter, and enables the scattering intensity to be interpreted in terms of the potential well in which the hydrogen atom resides. This may be accomplished by measuring the shape of the hydrogen wave function. The role of the hydrogen bond in the ferroelectric phase transition was studied in KHCO_3, and the shape of the crystal potential was studied by measuring S (Q,epsilon).

日本-英国中子散射合作是日本国家高能物理实验室（KEK）和英国科学与工程研究理事会（SERC）之间协议的结果。成立于1986年，旨在促进日本和英国科学家在脉冲中子散射领域的科学合作和交流。1994年日英合作项目在高温超导体及相关材料领域的主要工作包括用MARI测量高温铜氧化物La_Sr_CuO_4的动态结构因子S（Q，Q）<1.85><0.15>。这些实验揭示了与YBa_2Cu_3O_7不同的高能磁涨落，其能量可达300 meV。研究了一维海森堡反铁磁体CsVCl_3（S=3/2）的量子效应。使用MARI，他们能够确定磁激发的全色散，与75 meV的区边界能量。这些测量的关键结果之一是，在区中心有nogap被发现在整数自旋的情况下。氢在许多固体材料的性能中起着重要的作用。中子可以获得关于其在结构中的位置及其动力学行为的信息。量子理论对于解释后者是必要的，并且能够用氢原子所处的势阱来解释散射强度。这可以通过测量氢波函数的形状来实现。本文研究了氢键在KHCO_3铁电相变中的作用，并通过测量S（Q，ε）研究了晶体势的形状。