Speaker
Description
In commensurate twisted homobilayers, purely radial Rashba spin-orbit fields can emerge due to the interaction of the twisted hidden Rashba spin-orbit coupling (SOC) from each layer [1]. We calculate the band structures and the spin-orbit fields close to the high symmetry points $K$ and $\Gamma$ of commensurate twisted transition-metal dichalcogenide homobilayers (WSe$_2$ and NbSe$_2$) from first principles using density functional theory (DFT) calculations. The observed in-plane DFT spin textures are mostly radial and can in large parts be described by a model Hamiltonian, which consists of two continuum models for the two layers, including SOC terms and interacting by a general (spin-conserving) interlayer coupling. We additionally investigate the effects of an electric field, different lateral shifts and increasing interlayer distance, all three of which can bring back the radial Rashba structure to a tangential one.
Acknowledgements
We acknowledge support by the FLAG ERA JTC 2021 project 2DSOTECH. T.N. and J.F. were also supported by the European Union Horizon 2020 Research and Innovation Program 881603 (Graphene Flagship).
References
[1] Frank et al, "Emergence of radial Rashba spin-orbit fields in twisted van der Waals heterostructures", Physical Review B 109, L241403 (2024).
