Researchers from the Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC and BIST have reported a theoretical framework and numerical confirmation for fully efficient spin-charge interconversion in graphene. Efficient conversion of charge current into spin current is a central objective in spintronics, and the intrinsic properties of graphene make it an attractive platform to explore this phenomenon.
Joaquín Medina Dueñas, Santiago Giménez de Castro, Jose H. Garcia, and Stephan Roche from ICN2 demonstrate that a complete conversion can be achieved by controlling the coupling between spin and pseudospin degrees of freedom. The study shows that a combined spin-pseudospin operator remains conserved in graphene, enabling fully efficient spin-charge conversion through the Rashba-Edelstein effect. The results also reveal the presence of a spin Hall effect that is resilient to disorder, indicating a stable mechanism for spin transport in realistic graphene systems.
The work analyzes how spin-orbit coupling, lattice symmetry, and external fields influence spin-pseudospin entanglement. By manipulating graphene’s structure - through edge terminations, strain, or proximity effects - the researchers demonstrate that the Rashba effect, resulting from structural asymmetry, plays a decisive role in determining the spin polarization of carriers. The combination of Rashba and Kane-Mele spin-orbit interactions is shown to offer control over the spin state, suggesting strategies for designing efficient spin filters and polarizers.
Further analysis of graphene heterostructures confirms that the spin-charge conversion efficiency remains high even in the presence of imperfections such as staggered potentials or valley-Zeeman coupling. Quantum transport simulations in disordered systems support the robustness of these effects under realistic material conditions.
This work establishes a direct connection between graphene’s lattice symmetry and its spin-conversion efficiency, providing a basis for the controlled design of spintronic devices using two-dimensional materials. The results highlight the potential of spin-pseudospin correlations as a mechanism to tailor spin transport properties for future low-power electronics, spin-based logic, and quantum technologies.