Suchergebnisse

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. ; This work is supported by the Spanish MINECO under the Maria de Maeztu Units of Excellence Programme (MDM-2016-0618) and under projects MAT2015-65159-R and MAT2017-82071-ERC and by the European Union H2020 under the Marie Curie Actions (QUESTECH). The work in ICN2 is supported by Spanish MINECO under Severo Ochoa program (Grant No. Sev-2017-0706). S.R. and J.H.G. acknowledge support from the European Union Seventh Framework Programme under grant agreement no. 785219 Graphene Flagship and the computational resources from PRACE and the Barcelona Supercomputing Center (project no. 2015133194). M. V. acknowledges funding received from la Caixa foundation.

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. ; This work is supported by the Spanish MINECO under the Maria de Maeztu Units of Excellence Programme (MDM-2016-0618) and under projects MAT2015-65159-R, RTI2018-094861-B-100, MAT2017-88377-C2-2-R, and MAT2017-82071-ERC, and by the European Union H2020 under the Marie Curie Actions (794982-2DSTOP and 766025-QuESTech). N.O. thanks the Spanish MINECO for a Ph.D. fellowship (grant no. BES-2017-07963). V.T.P. acknowledges postdoctoral fellowship support "Juan de la Cierva-incorporación" program by the Spanish MINECO (grant no. FJCI-2017-34494).