MRSEC Seminar: Dr. Vardeny
Wednesday January 25, 2012
Professor Z. Valy Vardeny
Distinguished Professor, Department of Physics & Astronomy, University of Utah
Presented by the Departments of Materials Science and Engineering & Metallurgical Engineering
Organic semiconductors have been used as active layer in devices such as organic light-emitting diodes (OLEDs), photovoltaic cells, field-effect transistors, and lasers. Recently there has been a growing interest in spin and magnetic field effects in these materials. This include optically detected magnetic resonance where long spin coherence time was demonstrated; OLEDs where substantive magneto-electroluminescence and magneto-conductance were obtained; and organic spin valves (OSV) where spin injection from ferromagnetic (FM) electrodes was obtained. The interest in spin transport in organic semiconductors has been motivated by the weak spin-orbit interaction that is caused by the light building block elements such as carbon and hydrogen, and the small hyperfine interaction (HFI) with the nuclei.
In this talk the status of the young field of ‘Organic Spintronics’ will be reviewed. The necessary ingredients needed for the success of this field will be summarized, and evaluated by recent experiments. In particular the role of the HFI in magneto-transport will be elucidated via the isotope effect. Three applications of Organic Spintronics will be discussed: organic diodes with two FM electrodes for use as OSV; with one FM electrode for magnetic detectors; and organic diodes with no FM electrodes as magnetic sensors.