Graphene is an excellent material for long distance spin transport but allows little spin manipulation. Transition metal dichalcogenides imprint their strong spin-orbit coupling into graphene via proximity effect, and it has been predicted that efficient spin-to-charge conversion due to spin Hall and Rashba-Edelstein effects could be achieved. Here, by combining Hall probes with ferromagnetic electrodes, we unambiguously demonstrate experimentally spin Hall effect in graphene induced by MoS2 proximity and for varying temperature up to room temperature. The fact that spin transport and spin Hall effect occur in different parts of the same material gives rise to a hitherto unreported efficiency for the spinto-charge voltage output. Remarkably for a single graphene/MoS2 heterostructure-based device, we evidence a superimposed spin-to-charge current conversion that can be indistinguishably associated with either the proximity-induced Rashba-Edelstein effect in graphene or the spin Hall effect in MoS2. By comparing our results to theoretical calculations, the latter scenario is found the most plausible one. Our findings pave the way towards the combination of spin information transport and spin-to-charge conversion in two-dimensional materials, opening exciting opportunities in a variety of future spintronic applications.The efficient transport and the manipulation of spins in the same material are mutually exclusive as they would require simultaneously weak and strong spin-orbit coupling (SOC) respectively. Graphene, due to its low intrinsic SOC, is proven to be an outstanding material that can transport spins over long distance of tens of micrometres 1-10 . For the same reason, the generation and tuning of spin currents in graphene are out of reach, limiting its capability to active spintronic device functionalities and related applications. To solve this issue, methods to artificially induce SOC in graphene have been explored. For instance, the SOC in graphene has been enhanced by chemical doping [11][12][13][14][15][16][17] or by proximity-induced coupling with materials possessing large SOC [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] . The latter method is more convenient since the chemical properties of graphene are not altered, whereas its high-quality electronic transport properties are preserved.Transition metal dichalcogenides (TMDs) with chemical formula MX2 (M=Mo, W and X=S, Se) are layered materials of semiconducting nature displaying unique combined electronic, optical, spintronic and valleytronic properties [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] . They possess a strong intrinsic SOC of tens of meV, few orders larger than that of pristine graphene 36,37 . Accordingly, a large intrinsic spin Hall effect (SHE) has been theoretically predicted in TMDs 38 . However, its experimental observation remains elusive because of the technical difficulties to inject and detect spin information into these materials 49,50 . Only recently, a spin-orbit torque experim...

Efficient and versatile spin-to-charge current conversion is crucial for the development of spintronic applications, which strongly rely on the ability to electrically generate and detect spin currents. In this context, the spin Hall effect has been widely studied in heavy metals with strong spinorbit coupling. While the high crystal symmetry in these materials limits the conversion to the orthogonal configuration, unusual configurations are expected in low symmetry transition metal dichalcogenide semimetals, which could add flexibility to the electrical injection and detection of pure spin currents. Here, we report the observation of spin-to-charge conversion in MoTe2 flakes, which are stacked in graphene lateral spin valves. We detect two distinct contributions arising from the conversion of two different spin orientations. In addition to the conventional conversion where the spin polarization is orthogonal to the charge current, we also detect a conversion where the spin polarization and the charge current are parallel. Both contributions, which could arise either from bulk spin Hall effect or surface Edelstein effect, show large efficiencies comparable to the best spin Hall metals and topological insulators. Our finding enables the simultaneous conversion of spin currents with any in-plane spin polarization in one single experimental configuration.Symmetry is a unifying principle that governs all aspects of Physics, from the model of atomic orbitals to the Landau theory of phase transitions. The physical properties of crystalline solids are also highly constrained by symmetry 1 and, in turn, as symmetry is progressively lowered through the 32 crystallographic point groups, novel transport effects emerge, such as the non-linear Hall effect 2 , the spin galvanic effect 3 and the valley magnetoelectricity 4 in non-centrosymmetric crystals, and the magnetochiral anisotropy 5 in chiral crystals. Crystal symmetry dictates also the geometry of a phenomenon that has attracted a lot of attention in recent years, the spin Hall effect (SHE) or its reciprocal effect [inverse SHE (ISHE)], which are generally observed in materials possessing strong spin-orbit coupling (SOC), and enables the interconversion between charge and spin currents. In conventional spin Hall materials, high crystal symmetry imposes that injecting a charge current density ( ) can only result in a transverse spin current density ( ) with a spin polarization ( ) orthogonal to both and (Figure 1a) 6 . SHE/ISHE are crucial effects for the electrical generation or detection of spin current, required in applications such as spin-orbit torque memories 7,8,9 and spin-based logic devices 10,11 . These applications would highly benefit from more versatile SHE/ISHE configurations which can be obtained by lifting the constraints imposed by high crystal symmetry and enabling unusual spin-to-charge conversion geometries in low-symmetry crystals 12,13,14 (Figures 1b,c).

The proximity effect opens ways to transfer properties from one material into another and is especially important in two-dimensional materials. In van der Waals heterostructures, transition metal dichalcogenides (TMD) can be used to enhance the spin-orbit coupling of graphene leading to the prediction of gate controllable spin-to-charge conversion (SCC). Here, we report for the first time and quantify the SHE in graphene proximitized with WSe2 up to room temperature. Unlike in other graphene/TMD devices, the sole SCC mechanism is the spin Hall effect and no Rashba-Edelstein effect is observed. Importantly, we are able to control the SCC by applying a gate voltage. The SCC shows a high efficiency, measured with an unprecedented SCC length larger than 20 nm. These results show the capability of two-dimensional materials to advance towards the implementation of novel spin-based devices and future applications.The integration of spintronic devices into existing electronic technology will strongly depend on the all-electrical control of spin currents, with a crucial role being played by the interconversion between charge currents and spin currents. The latter can be achieved by the (inverse) spin Hall effect [(I)SHE] in bulk conductors 1-3 , as well as by the (inverse) Rashba-Edelstein effect [(I)REE] in two-dimensional (2D) systems and interfaces 4 , allowing ferromagnet(FM)-free electrical generation and detection of spin currents. While the experimental observation of the (I)SHE and (I)REE have been successful in different systems 3,5,6 , the transition from the laboratory to industrial applications will require careful device design and material choice to achieve large enough signals for practical implementation [7][8][9][10] .

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Spin-orbit coupling in graphene can be enhanced by chemical functionalization, adatom decoration or proximity with a van der Waals material. As it is expected that such enhancement gives rise to a sizeable spin Hall effect, a spin-to-charge current conversion phenomenon of technological relevance, it has sparked wide research interest. However, it has only been measured in graphene/transition metal dichalcogenide van der Waals heterostructures with limited scalability. Here, we experimentally demonstrate spin Hall effect up to room temperature in bilayer graphene combined with a nonmagnetic insulator, an evaporated bismuth oxide layer. The measured spin Hall effect raises most likely from an extrinsic mechanism. With a large spin-to-charge conversion efficiency, scalability, and ease of integration to electronic devices, we show a promising material heterostructure suitable for spin-based device applications.