The use of graphene in spintronic devices depends, among other things, on its ability to convert a spin excitation into an electric charge signal, a phenomenon that requires a spin-orbit coupling (SOC). Here we report the observation of two effects that show the existence of SOC in large-area CVD grown single-layer graphene deposited on a single crystal film of the ferrimagnetic insulator yttrium iron garnet (YIG). The first is a magnetoresistance of graphene induced by the magnetic proximity effect with YIG. The second is the detection of a dc voltage along the graphene layer resulting from the conversion of the spin current generated by spin pumping from microwave driven ferromagnetic resonance into a charge current, which is attributed to the inverse Rashba-Edelstein effect.

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The generation of spin currents by thermal gradients applied to a magnetic film is known as the spin Seebeck effect (SSE). The SSE is usually detected by an electric voltage generated in a metallic layer in contact with the magnetic film produced by the spin to charge current conversion through the inverse spin Hall effect (ISHE). The SSE has been widely studied in bilayers made of the insulating ferrimagnet yttrium iron garnet (YIG) and metals with large spin orbit coupling, such as platinum. Recently, the SSE has been observed in bilayers made of the antiferromagnets MnF2 and Cr2O3 with Pt at low temperatures and high magnetic fields. Here, we report measurements of the SSE at room temperature and low magnetic fields in bilayers made of well textured films of antiferromagnetic NiO with several metals. The detection of the spin current generated by the thermal gradient in the NiO layer is made by means of the ISHE in the nonmagnetic metals Pt and Ta, in the AF metal IrMn, and in the ferromagnetic metal Ni81Fe19 (permalloy). The measured spin Seebeck effect in NiO/Pt has the same sign and is about one order of magnitude smaller than in YIG/Pt.

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We report the spin to charge current conversation in an intrinsic topological insulator (TI) (Bi0.22Sb0.78)2Te3 film at room temperature. The spin currents are generated in a thin layer of permalloy (Py) by two different processes, spin pumping (SPE) and spin Seebeck effects (SSE).In the first we use microwave-driven ferromagnetic resonance of the Py film to generate a SPE spin current that is injected into the TI (Bi0.22Sb0.78)2Te3 layer in direct contact with Py. In the second we use the SSE in the longitudinal configuration in Py without contamination by the Nernst effect made possible with a thin NiO layer between the Py and (Bi0.22Sb0.78)2Te3 layers.The spin-to-charge current conversion is attributed to the inverse Edelstein effect (IEE) made possible by the spin-momentum locking in the electron Fermi contours due to the Rashba field.The measurements by the two techniques yield very similar values for the IEE parameter, which are larger than the reported values in the previous studies on topological insulators.

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Pure spin current can be detected by its conversion into charge current in nanometer thick nonmagnetic metal layer with large spin-orbit coupling by means of the inverse spin Hall effect (ISHE). Recently, it has been shown that the metallic ferromagnet Permalloy (Py) can also be used as spin current detector in experiments in which an ISHE voltage is created in a Py layer in contact with the insulating ferromagnet yttrium iron garnet (YIG) under a thermal gradient in the longitudinal spin Seebeck configuration. Here, we report experiments with microwave driven spin pumping in heterostructures made with single crystal YIG film and a nanometer thick Py or Pt layer that show that Py behaves differently than nonmagnetic metals as a spin current detector. The results are attributed to the competition between the spin currents generated by the dynamics of the magnetizations in YIG and in Py, which are exchange coupled at the interface.