Condensed Matter Seminar

Markus Wohlgenannt
Department of Physics and Astronomy, University of Iowa

Tuesday, February 3, 2009; 4:00 pm in JFB 334

Magnetoresistance and spin-transport in organic semiconductor thin-film devices

Organic magnetoresistance is a recently discovered large, room-temperature magnetoresistive effect observed in organic semiconductor devices based entirely on non-magnetic materials. We will present our experimental results and show that the effect is caused by hyperfine interaction. Indeed, model simulations based on hopping of carriers through the disordered organic film while simultaneously treating the interaction of the carrier spin with the hyperfine field can explain many of the experimental results. Finally, we will explore the limitations that hyperfine interaction imposes on the spin-diffusion length, which is important in spin-valve applications of organic semiconductors.