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. ***
