Distinguishing spin pumping from spin rectification in lateral spin pumping device architectures based on doped organic semiconductors

Abstract

Over the last two decades organic spintronics has developed into a striving field with exciting reports of long spin diffusion lengths and spin relaxation times in organic semiconductors (OSCs). Easily processed and inexpensive, OSCs are considered a potential alternative to inorganic materials for use in spintronic applications. Spin currents have been detected in a wide range of materials; however, there is still uncertainty over the origin of the signals. Recently, we explored spin transport through an organic semiconductor with lateral spin injection and detection architectures, where the injected spin current is detected nonlocally via spin-to-charge conversion in an inorganic detector. In this work we show that the widely used control experiments like linear power dependence and inversion of the signal with the magnetic field are not sufficient evidence of spin transport and can lead to an incorrect interpretation of the signal. Here, we use in-plane angular dependent measurements to separate pure spin signal from parasitic effects arising from spin rectification. Apart from well established anisotropic magnetoresistance and the anomalous Hall effect, we observe another spurious effect originating in Py and having the same angular symmetry as the inverse spin Hall effect (ISHE), which suggests it might be a self-induced ISHE.