This award supports computational and theoretical research and education on strongly correlated electron materials. The work involves algorithmic development, large scale computation, and the use of computation as a discovery tool. The main focuses of the research include:
(i) Focus on demonstrating that the colossal magnetoresistance effect occurs in realistic microscopic materials of the double-exchange family. The PIs aim to include in Monte Carlo simulations all the ingredients believed to be important to explain this phenomenon, the Hund coupling, phonons, superexchange, and quenched disorder.
(ii) There is experimental evidence that an electronic reconstruction occurs at the interface of certain materials, particularly the transition metal oxides. These effects suggest that analogs of semiconducting heterostructures can be developed using complex oxides. The PIs will explore a variety of interfaces including manganite-manganite, superconductor-manganite, and manganite-titanate. The properties of these artificially prepared systems will be studied.
(iii) The PIs will investigate a real space model for diluted magnetic semiconductors that reproduces the valance bands of the parent compound, takes into account random manganese doping and spin-orbit interaction, and can be studied with unbiased numerical techniques. Results will be meaningfully compared with experiments for a variety of compounds.
(iv) The PIs will use the time dependent density matrix renormalization group technique to study transport in models for molecules, polymers, transformation of a Mott insulator into a metal, and the sudden expansion of a fermionic gas.
This award supports the training of graduate students in advanced computational methods for condensed matter theory and materials research. The research activity involves international collaboration with researchers in Latin America.
NON-TECHNICAL SUMMARY: This award supports computational and theoretical research and education on complex materials that exhibit unusual electronic properties and new states of matter which are a consequence of strong interactions among electrons. Using theoretical concepts and advanced computation, the PIs aim to gain insight into new states of matter, effects where small magnetic fields can lead to dramatic changes in the resistance to the flow of electric current, and how charge moves through molecules. They also hope to discover novel magnetic phenomena in semiconductors and semiconductor heterostructures, and more. All these lay the foundations for future technological applications that have the potential to revolutionize electronics and our understanding of certain classes of materials. This activity helps to keep America competitive in the 21st century, not only through intellectual advances but through education of the next generation of scientists able to use computation as a discovery tool and able to function competitively in a global economy.
