Reliable Spin Valves of Conjugated Polymer Based on Mechanically Transferrable Top Electrodes

Organic spintronic devices present one of the most appealing technologies for future spintronic devices by taking advantage of the spin degree of freedom. Conjugated polymers are attractive for the exemplified device of organic spin valves (OSVs) due to their weak spin-orbit coupling, solution-processability, low production cost, and mechanical flexibility. However, the performance of polymer SVs is a matter of debate, as the evaporated top ferromagnetic (FM) electrode will penetrate into the organic layer during a typical fabrication process, especially in the device with an organic layer thickness of nanometers. It will cause a severe problem in controllable and reproducible spin manipulations, not to mention the clarification of the spin-dependent transport mechanism. Here, a universal, simple, and low-cost method based on a transferred electrode is developed for a polymer spin valve with stable and reliable state operation. It is demonstrated in an OSV device with a vertical structure of La_2/3Sr_1/3MnO₃ (LSMO)/P3HT/AlO _x/Co/Au that this approach not only builds a damage-free interface between magnetic electrodes and an organic spacer layer but also can be generalized for other devices with delicate active layers. Furthermore, a multistate writing and reading prototype is achieved on the premise of robust and quick magnetic response. The results reveal the importance of a spinterface and effective thickness of the organic layer in fundamental spintronic research and may lead to a strong potential in future flexible, large-area, and robust organic multifunctional circuits.