Experiments on Spin 1/2, One Dimensional, Heisenberg Ferromagnets

磁性材料在计算机存储器和磁记录设备中非常重要。目前还不完全清楚是什么控制了磁相互作用，从而也就决定了材料的磁性。本提案是审查模型系统的一系列努力之一，在这些模型系统中，不同的磁相互作用可以被隔离、详细研究和更好地理解。最近合成的体系符合自旋1/2的一维海森堡铁磁体模型。本提案的目标是处理该模型对非线性现象、磁-结构相关性和动力学性质有影响的各个方面。为此，将有一个详细的研究来观察从自旋波到束缚磁振子对磁化率的支配作用。还将通过测量单轴应力下样品的磁化率来研究超交换作用与键角的关系。其他实验将检查显示自旋玻璃行为的准一维混合金属系统的相图和多临界点。

Magnetic materials are of great importance in computer memories and magnetic recording devices. It is not fully understood what controls magnetic interactions, and hence the magnetic properties of materials. The present proposal is one of a number of efforts to examine model systems in which different magnetic interactions can be isolated, studied in detail and better understood. Systems have recently been synthesized which conform to the model of a spin 1/2, one dimensional Heisenberg ferromagnet. The goal of the present proposal is to address aspects of the model that have implications for nonlinear phenomena, magnetic-structural correlations and dynamic properties. To this end, there will be a detailed study to observe the crossover from spin wave to bound magnon domination of magnetic susceptibilities. The dependence of the superexchange interaction on bond angle will also be studied by measuring the magnetic susceptibility of samples placed under uniaxial stress. Other experiments will examine the phase diagrams and the multicritical point of quasi-one- dimensional mixed metal systems showing spin glass behavior.