Nuclear Hyperpolarization in Semiconductors

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Technical AbstractThe work seeks to understand and control the physical processes leading to nuclear spin angular momentum. Massively athermal nuclear spin polarizations will be generated via electron-nuclear cross-relaxation in semiconducting materials, where the electrons have been eigenstate-prepared by optical pumping or spin-injection methods. The work will begin with a systematic study of electron-nuclear cross relaxation in a host of materials that are engineered to test mechanisms for nuclear hyperpolarization. In the course of these studies nuclear hyperpolarization in new materials is anticipated, and if the past is any indication, new phenomenology will also be manifest. This work will use the newly developed understanding of nuclear hyperpolarization to design new experiments and build devices that test and exploit electron-nuclear couplings. These devices include spin-injection delivery of massive nuclear polarization to inorganic solids, the preparation of nanoscale regions of hyperpolarization, and the coupling of these and other devices so as to prepare reservoirs of highly spin-polarized solvents.Non-Technical AbstractThe nuclei of many atoms on the Periodic Table possess a property known as spin, a property that has enabled technologies such as magnetic resonance imaging, or MRI. There are many other technologies that could exploit this fundamental property of atoms, yet these technologies are precluded from commercial development because the sensitivity of the methods that detect nuclear spin is too low. The electrons that comprise atoms and molecules also have spin, and this electron spin can be manipulated with light and magnetic materials. This project will support two students, one each at UC Berkeley and City College of New York, to manipulate electron spins so that nearby nuclear spins can be detected with greatly enhanced sensitivity. There are two reasons for conducting these studies: the first is that the interaction between electrons and nuclear spins is of inherent scientific interest; the second is that control of nuclear spins in the vicinity of electrons spins could both greatly enhance the sensitivity of methods such as MRI, but could also lead to the design of new quantum computers.