Quantum Aspects of Condensed Matter

9531575 Chakravarty这笔赠款是对一位职业生涯中期凝聚态理论家领导的正在进行的计划的更新。在这项资助中感兴趣的主题是量子磁性和非费米液体基态。在量子磁学中，PI建议计算二维量子反铁磁体的动态结构因子。计算将有助于理解中子散射测量，并提供对一类特殊的短波长和高能费米子激发(自旋)的洞察。此外，还计划对表现出“巨大”磁阻的材料进行研究。利用标度和有效场的概念对非费米液体进行研究，将涉及到现象学和可能的分类。在一个材料要么是金属，要么是非金属的世界里，目前的研究集中在一类材料上，这些材料的电阻率显示出金属特性，但它们的所有其他性质(比热、磁化率)都相当反常。这笔赠款将发展一种关于这种非费米液体的现象学理论。这笔拨款还包括在二维量子反铁磁体方面的工作。作为一个理论问题，这解决了自PI早期开创性贡献以来的一些悬而未决的问题。***

9531575 Chakravarty This grant is a renewal of an ongoing program led by a mid- career condensed matter theorist. The topics of interest in this grant are Quantum Magnetism and non-Fermi liquid ground sates. In quantum magnetism, the PI proposes to calculate the dynamic structure factor of a 2-dimensional quantum antiferromagnet. The calculation will help understand the neutron scattering measurements and provide insight into a special class of fermionic excitations (spinons) at short wavelengths and high energies. Also planned is a study of the materials which exhibit "colossal" magnetoresistance. The research on non-Fermi liquids, using concept of scaling and effective fields, will involve phenomenology and possible classification. %%% In a world where materials are either metallic or nonmetallic, current research is converging on a class of materials that show metallic character in resistivity but all of their other properties (specific heat, magnetic susceptibility) are quite anomalous. This grant will develop a phenomenological theory of such non-Fermi liquids. The grant also includes work on quantum antiferromagnets in 2-dimension. As a theoretical problem this addresses some outstanding questions since the PI's earlier seminal contributions. ***