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 the ...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 the spin Hall effect in graphene induced by MoS2 proximity and for varying temperatures up to room temperature. The fact that spin transport and the spin Hall effect occur in different parts of the same material gives rise to a hitherto unreported efficiency for the spin-to-charge voltage output. Additionally, 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 a comparison of our results to theoretical calculations, the latter scenario is found to be the most plausible one. Our findings pave the way toward 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.
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 spin–orbit 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.
The proximity effect opens ways to transfer properties from one material into another and
is especially important in two-dimensional (2D) materials. In van der Waals
heterostructures, transition ...metal dichalcogenides (TMDs) 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 spin
Hall effect (SHE) in graphene proximitized with WSe2 up to room temperature.
Unlike in other graphene/TMD devices, the sole SCC mechanism is the SHE 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 2D materials to advance
toward the implementation of novel spin-based devices and future applications.
The ultimate goal of spintronics is achieving electrically controlled coherent manipulation of the electron spin at room temperature to enable devices such as spin field-effect transistors. With ...conventional materials, coherent spin precession has been observed in the ballistic regime and at low temperatures only. However, the strong spin anisotropy and the valley character of the electronic states in 2D materials provide unique control knobs to manipulate spin precession. Here, by manipulating the anisotropic spin-orbit coupling in bilayer graphene by the proximity effect to WSe2, we achieve coherent spin precession in the absence of an external magnetic field, even in the diffusive regime. Remarkably, the sign of the precessing spin polarization can be tuned by a back gate voltage and by a drift current. Our realization of a spin field-effect transistor at room temperature is a cornerstone for the implementation of energy efficient spin-based logic.
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 ...sizable 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 the spin Hall effect up to room temperature in graphene combined with a nonmagnetic insulator, an evaporated bismuth oxide layer. The measured spin Hall effect arises 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.
A charge density wave (CDW) represents an exotic state in which electrons are arranged in a long‐range ordered pattern in low‐dimensional materials. Although the understanding of the fundamental ...character of CDW is enriched after extensive studies, its practical application remains limited. Here, an unprecedented demonstration of a tunable charge‐spin interconversion (CSI) in graphene/1T‐TaS2 van der Waals heterostructures is shown by manipulating the distinct CDW phases in 1T‐TaS2. Whereas CSI from spins polarized in all three directions is observed in the heterostructure when the CDW phase does not show commensurability, the output of one of the components disappears, and the other two are enhanced when the CDW phase becomes commensurate. The experimental observation is supported by first‐principles calculations, which evidence that chiral CDW multidomains in the heterostructure are at the origin of the switching of CSI. The results uncover a new approach for on‐demand CSI in low‐dimensional systems, paving the way for advanced spin‐orbitronic devices.
An unprecedented tunable charge‐spin interconversion (CSI) is observed in graphene/1T‐TaS2 van der Waals heterostructures by manipulating the charge density wave (CDW) phases in 1T‐TaS2. The output of one of the CSI components switches off with the commensurability of the CDW phases. First‐principles calculations support that chiral CDW multidomains in the heterostructure are at the origin of the switching of CSI.
Graphene is a light material for long-distance spin transport due to its low spin–orbit coupling, which at the same time is the main drawback for exhibiting a sizable spin Hall effect. Decoration by ...light atoms has been predicted to enhance the spin Hall angle in graphene while retaining a long spin diffusion length. Here, we combine a light metal oxide (oxidized Cu) with graphene to induce the spin Hall effect. Its efficiency, given by the product of the spin Hall angle and the spin diffusion length, can be tuned with the Fermi level position, exhibiting a maximum (1.8 ± 0.6 nm at 100 K) around the charge neutrality point. This all-light-element heterostructure shows a larger efficiency than conventional spin Hall materials. The gate-tunable spin Hall effect is observed up to room temperature. Our experimental demonstration provides an efficient spin-to-charge conversion system free from heavy metals and compatible with large-scale fabrication.
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 MoS
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 spin-to-charge voltage output. Remarkably for a single graphene/MoS
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 MoS
. 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.
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