Manipulating Multi-Spin Dynamics in Systems Targeting Organic Spintronics

Intellectual Merits: Controlling the spin dynamics of complex multi-spin molecular systems is a major goal in spintronics and quantum information processing. Fast photo-initiated electron transfer within covalently-linked organic donor-acceptor molecules having specific donor-acceptor (D-A) distances and orientations results in the formation of spin-entangled electron-hole pairs (i.e. spin-correlated radical ion pairs, SCRPs) having well-defined initial spin configurations and magnetic spin-spin interactions. Time-resolved electron paramagnetic resonance (TREPR) and pulsed EPR techniques provide important means of manipulating and controlling these coherent spin states. Organic SCRPs display coherent spin motion for up to approximtely 100 ns, which makes it possible that this coherence may provide the basis for new quantum information processing strategies based on organic molecules. For example, we and others have investigated the influence of additional spins on the spin dynamics of SCRPs with restricted distances and orientations. Multi-spin organic molecules and materials have already shown promise as novel magnetic materials. A greater fundamental understanding of the factors controlling spin dynamics in complex, yet versatile organic multi-spin systems is necessary before construction of spintronic devices based on them is feasible. Our new research will principally focus on the demanding task of controlling spin coherence within organic molecular arrays using SCRPs in tailored covalent organic structures. The specific goals of this project are to investigate four questions that are important for understanding spin coherence in organic molecules and the development of organic spintronics: � What is the scope of spin coherence transfer by optical excitation of a SCRP? � What factors determine coherence dephasing in SCRPs? � Can coherent spin states be transported (teleported) over long distances using SCRPs? � Can the spin dynamics of SCRPs be controlled to store and recover spin polarization in nuclear spins?