High-Field Magnetoresistance Effects and Temperature-Dependent Spin Relaxation in Rubrene Nanowire Spin Valves

In this work we discuss the high-field magnetoresistance effects and temperature-dependent spin relaxation in rubrene nanowire spin valves. Rubrene thin film spin valves have been studied by several groups in the past since this material can potentially offer long spin relaxation length (L-s). However, the Ls values reported so far have been low, typically similar to 10 nm at low temperatures (similar to 10K). Recently we have reported a vertical spin valve device using rubrene spacer, in which rubrene is patterned in a nanowire array geometry. Such patterning leads to significant suppression of spin relaxation and we have reported spin relaxation length of 47 nm at similar to 10K in rubrene nanowires. In this work we present the high field magnetoresistance measurements performed on rubrene nanowires and discuss the possible origins of these effects. Further, we discuss possible origin of the observed temperature-dependence of spin relaxation length.