Structural, Magnetic and Magnetoresistive Properties of PTCTE Based Organic Spin Valves

Organic semiconductors are very promising materials in the field of spintronic devices like spin valves (SV) because of large spin relaxation time in ¿-conjugated molecules and the advantage of rather simple and low energy consuming device fabrication techniques. Most of the studies of spin injection in organic semiconductors focused on hole transport materials and one electron transport material: the tris(8-hydroxyquinoline) aluminum (Alq₃). In this article, we present our first results on SV based on a perylene derivative, PTCTE (PTCTE: tetraethyl perylene 3, 4, 9, 10-tetracarboxylate). Perylene molecules were traditionally used as electron transport materials in optoelectronic devices like OLED (organic electroluminescent diodes) and solar cells. NiFe/PTCTE/Co devices were prepared by dc sputtering for the electrodes (with direct or off axis sample configuration for the upper electrode), and vacuum sublimation for the organic layer. CPP (current perpendicular to plane) devices geometry was obtained with millimetric contact masks determining a CPP spin valve area of 1 mm × 1 mm. Up to now, our best samples have a spin valve magnetic behavior and exhibit up to 3 % MR response at low temperature for a 300 nm organic spacer layer.