Spin and Orbital Edelstein effect in gated monolayer transition metal dichalcogenides

Abstract: The Edelstein effect consists of the non-equilibrium accumulation of magnetization in response to an applied electric field in systems with broken inversion symmetry. While the spin Edelstein effect (SEE), originating from spin moments, is well established, its orbital counterpart, where magnetization arises from orbital moment, has only recently begun to attract attention. In this work, we investigate the orbital Edelstein effect (OEE) in gated monolayer transition-metal dichalcogenides (TMDs), such as MoS2, by using first-principles density-functional calculations with both electron and hole doping. The gate-induced broken mirror symmetry produces a Rashba-type chiral spin/orbital angular momentum texture, which in turn leads to the Edelstein effect in response to an applied in-plane electric field. We find that for electron doping the Edelstein response is dominated by the orbital channel, whereas for hole doping the orbital and spin contributions are comparable. For the case of hole doping, both OEE and SEE are strongly enhanced by a small amount of strain, due to strain-driven shifts between the Gamma and K/K' valley energies. We derive analytical expressions for the spin and orbital Edelstein susceptibilities and evaluate their magnitudes from first-principles. Remarkably, the predicted OEE in gated monolayer TMDs is an order of magnitude larger than values reported in previously studied systems. Our results identify TMDs as promising platforms for studying the orbital Edelstein effect and highlight their potential applications in spintronics devices.