Materially-Predictive Theory of Magnetic Behavior and the Heavy Fermion State

点击翻译按钮获取中文摘要

This research is aimed at exploiting and extending capabilities for treating the reduced magnetic ordering and related phenomena, including magneto-optic behavior, associated with the highly correlated f-electron state on approaching or being in the heavy fermion state. Essentially, we have learned how to exhibit magnetic ordering properties in the correlated-electron state by projecting onto a site-centered basis. Our materially-predictive methodology involves two major stages: (1) the parameters in a lattice model hamiltonian containing both band-f hybridization and band-f coulomb exchange are calculated by a sequence of electronic structure calculations and, (2) a two-step sequence for finding the magnetic ordering properties (ground state and equilibrium behavior, magnetic excitations, critical behavior) first transforming the model hamiltonian into the language of resonant scattering theory to get an effective multipolar two-ion interaction and then using various methods we have developed to predict the observable properties on a wholly ab initio basis (no adjustable parameters or empirical information used). We will use this methodology to predict the approach to and nature of magnetic ordering in the heavy fermion state for seveal isostructural systems of experimental interest. Our methodology will be extended to include predicting (1) incremental specific heat associated with magnetic ordering, (2) pressure effects and elastic properties, (3) effects in high applied magnetic fields, (4) alloying including diluting the f-electron species. In addition, we will initiate studies on the role of explicit (interconfigurational) correlation effects on the magneto-optic behavior and on the conduction bands. %%% Computationally-intensive research will be undertaken to study the magnetic properties of materials in which the electrons behave as if their masses are many times their usual mass, ie, so-called heavy fermion systems. These highly correlated systems are difficult to treat using conventional techniques. The calculations proposed here are unique in coupling electronic structure calculations for these systems with many-body theory to describe these highly correlated systems from a first-principles approach.