Neutron Scattering Techniques Applied to the Investigation of Prototypical Magnetic Systems

9701339林恩这个项目将探索三个一般的研究途径。第一个涉及磁阻氧化物的结构和动力学。这项工作将使用极化和非极化中子散射技术来研究磁性和晶体结构，两者之间耦合的性质，以及弹簧和晶格的动力学激发。第二个领域涉及超导体中涡旋态的性质，当晶格无序时，以及稀土磁性有序发生时。最后一个感兴趣的领域涉及对各向同性铁磁性自旋动力学的研究。偏振光束技术将被用来分离诸如因瓦合金等反常系统中材料的纵向和横向自旋动力学。我们还将继续研究居里温度以下的纵向和横向涨落谱，以及它们作为外场函数的行为。这个项目将探索使用中子散射技术进行材料研究的三个一般途径。第一个涉及巨型磁阻氧化物的基本结构和磁性，以努力确定这些新系统中金属绝缘体转变的起源。第二个方面涉及对控制超导参数的材料性质的确定和理解，这些参数对商业应用具有重要意义，例如用于生产高临界电流材料的涡旋钉扎。最后一个领域涉及软磁材料的基本和实用性能，这些材料对变压器铁心、磁屏蔽等具有商业重要性。我们将特别强调因瓦类软磁材料，因为它们具有技术重要性，因为它们的密度不随温度变化，而不是大多数金属在加热时膨胀。***

9701339 Lynn This project will explore three general avenues of research. The first involves the structure and dynamics of the magnetoresistive oxides. This work will employ both polarized and unpolarized neutron scattering techniques to study the magnetic and crystal structures, nature of the coupling between these two, and the sping and lattice dynamical excitations. The second area concerns the nature of the vortex state in superconductors, when the lattice becomes disordered, and when the rare earth magnetic ordering occurs. The final area of interest involves the study of the spin dynamics of isotropic ferromagnetics. Polarized beam techniques will be used to separate the longitudinal and transverse spin dynamics of materials in anomalous systems such as Invar alloys. We will also continue our investigations of the longitudinal and transverse fluctuation spectra just below the Curie temperature, and their behavior as a function of applied field. %%% This project will explore three general avenues of materials research using neutron scattering techniques. The first involves the fundamental structural and magnetic properties of the colossal magnetoresistive oxides, in an effort to establish the origins of the metal insulator transition in these novel systems. The second aspect concerns a determination and understanding of the materials properties which control the superconducting parameters of central importanceto commercial applications, such as vortex pinning to produce high critical current materials. The final area concerns the fundamental and practical properties of soft magnetic materials, which are of commercial importance for transformer cores, magnetic shielding, etc. Particular emphasis will be placed on the Invar class of soft magnets, as these are of technical importance because their density does not chan ge with temperature, in contrast to most metals which expand upon heating. ***