Invited Paper MI-TuA1
Promises and Challenges of Organic Spintronics

Tuesday, November 8, 2016, 2:20 pm, Room 102B

While the term “Spintronics" was originally introduced as label for technologies that represent information through spin states rather than charge states, it is nowadays oftentimes used solely in the context of spin-polarization, spin-injection, and spin-transport effects, for all of which spin-orbit interaction plays an important role. Many organic semiconductors display only weak spin-orbit coupling and charge transport via hopping through localized electronic states which are exposed to hydrogen induced strong local and random hyperfine fields. These materials therefore appear at first glance to be entirely unsuitable for spintronics. However, they also exhibit pronounced spin-related effects not seen in materials with strong spin-orbit coupling^1-3 which can be used for alternative, different approaches to spintronics based, for instance, on spin-permutation symmetry states of charge carrier pairs which, in contrast to spin-polarization states, are not directly dependent on temperature and magnetic field strength⁴. Weak spin-orbit coupling can also promote long spin-coherence times and thus, allow for electrically readable spin memory of electron-⁵ or nuclear-spins⁶. The successful implementation of organic spintronics will require a fundamental understanding of the microscopic electronic processes that are to be utilized for such technologies. In this presentation, some of the progress as well as challenges⁷ for the exploration of these spin-dependent processes will be reviewed. Measurements of spin-coupling types and strengths of charge carriers will be discussed² as well as examples for unusual physical behaviors of these materials, such as an electrically detectable spin-Dicke effect caused by charge carrier spin collectivity⁸.or the presence of an inverse spin-Hall effect⁹.