Low-Dimensional Quantum Antiferromagnets

提出了一系列实验来探索具有新型协同量子效应的低维反铁磁材料的基态性质和激发。通过施加压力改变自旋-1链的哈密顿量的参数，探讨了零温度相变。详细研究了自旋-1/2链中的场致不相称软模式。具有竞争相互作用的量子系统的性质将通过具有次近邻违规的一维链和具有几何挫折的二维系统的实验来检验。研究将涉及晶体生长和表征，低温热力学测量，以及通过非弹性中子散射详细研究动力学特性。这项研究涉及磁性材料的生长和表征，这些材料的磁性很大程度上局限于沿一维或二维发生。磁性能在低温下变得明显，并且还受到静水压力的影响。这项研究将为磁学和高温超导材料领域提供基础信息。这些材料将通过磁测量和中子散射技术进行研究，中子散射技术反映了各种材料中原子磁体的动力学方面。＊＊＊

9302065 Reich A series of experiments are proposed to explore the ground state properties and excitations of low-dimensional antiferromagnetic materials that exhibit novel cooperative quantum effects. A zero- temperature phase transition will be explored by varying the parameters in the Hamiltonian of spin-1 chain through the application of pressure. A field-induced incommensurate soft mode in the spin-1/2 chain will be studied in detail. The properties of quantum systems with competing interactions will be examined through experiments on one-dimensional chains with next-nearest neighbor infractions and two-dimensional systems with geometrical frustration. The research will involve crystal growth and characterization, low-temperature thermodynamic measurements, and detailed studies of dynamical properties via inelastic neutron scattering. %%% This research involves the growth and characterization of materials which have magnetic properties largely constrained to occur along one- or two-dimensions. The magnetic properties become pronounced at low temperatures, and are also influenced by application of hydrostatic pressure. The research will provide fundamental information relevant to magnetism, and to the field of high-Tc superconducting materials. The materials will be investigated using magnetic measurements and by the technique of neutron scattering which reflects dynamical aspects of the atomic magnets in the various materials. ***