Staff directory Marc Vila Tusell

Publications

2019

  • Room-Temperature Spin Hall Effect in Graphene/MoS 2 van der Waals Heterostructures

    Safeer C.K., Ingla-Aynés J., Herling F., Garcia J.H., Vila M., Ontoso N., Calvo M.R., Roche S., Hueso L.E., Casanova F. Nano Letters; 2019. 10.1021/acs.nanolett.8b04368. IF: 12.279

    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 MoS 2 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/MoS 2 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 2 . 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. © 2019 American Chemical Society.


  • Tunable circular dichroism and valley polarization in the modified Haldane model

    Vila M., Hung N.T., Roche S., Saito R. Physical Review B; 99 (16, 161404) 2019. 10.1103/PhysRevB.99.161404. IF: 3.736

    We study the polarization dependence of optical absorption for a modified Haldane model, which exhibits antichiral edge modes in the presence of sample boundaries and has been argued to be realizable in transition metal dichalcogenides or Weyl semimetals. A rich optical phase diagram is unveiled, in which the correlations between perfect circular dichroism, pseudospin andvalley polarization can be tuned independently upon varying the Fermi energy. In particular, perfect circular dichroism and valley polarization are achieved simultaneously. This combination of optical properties suggests some interesting photonic device functionality (e.g., light polarizer) which could be combined with valleytronics applications (e.g., generation of valley currents). © 2019 American Physical Society.


2018

  • Spin transport in graphene/transition metal dichalcogenide heterostructures

    Garcia J.H., Vila M., Cummings A.W., Roche S. Chemical Society Reviews; 47 (9): 3359 - 3379. 2018. 10.1039/c7cs00864c. IF: 40.182

    Since its discovery, graphene has been a promising material for spintronics: its low spin-orbit coupling, negligible hyperfine interaction, and high electron mobility are obvious advantages for transporting spin information over long distances. However, such outstanding transport properties also limit the capability to engineer active spintronics, where strong spin-orbit coupling is crucial for creating and manipulating spin currents. To this end, transition metal dichalcogenides, which have larger spin-orbit coupling and good interface matching, appear to be highly complementary materials for enhancing the spin-dependent features of graphene while maintaining its superior charge transport properties. In this review, we present the theoretical framework and the experiments performed to detect and characterize the spin-orbit coupling and spin currents in graphene/transition metal dichalcogenide heterostructures. Specifically, we will concentrate on recent measurements of Hanle precession, weak antilocalization and the spin Hall effect, and provide a comprehensive theoretical description of the interconnection between these phenomena. © 2018 The Royal Society of Chemistry.


  • Tailoring emergent spin phenomena in Dirac material heterostructures

    Khokhriakov D., Cummings A.W., Song K., Vila M., Karpiak B., Dankert A., Roche S., Dash S.P. Science Advances; 4 (9, aat9349) 2018. 10.1126/sciadv.aat9349. IF: 11.511

    Dirac materials such as graphene and topological insulators (TIs) are known to have unique electronic and spintronic properties. We combine graphene with TIs in van der Waals heterostructures to demonstrate the emergence of a strong proximity-induced spin-orbit coupling in graphene. By performing spin transport and precession measurements supported by ab initio simulations, we discover a strong tunability and suppression of the spin signal and spin lifetime due to the hybridization of graphene and TI electronic bands. The enhanced spin-orbit coupling strength is estimated to be nearly an order of magnitude higher than in pristine graphene. These findings in graphene-TI heterostructures could open interesting opportunities for exploring exotic physical phenomena and new device functionalities governed by topological proximity effects. Copyright © 2018 The Authors.