Coupled Spin-Valley, Rashba Effect, and Hidden Spin Polarization in WSi2N4 Family

Using first-principles calculations, we report the electronic properties with a special focus on the band splitting in the WSi 2 N 4 class of materials. Due to the broken inversion symmetry and strong spin–orbit coupling, we detect coupled spin-valley effects at the corners of the first Brillouin zone (BZ). Additionally, we observe cubically and linearly split bands around the Γ and M points, respectively. The in-plane mirror symmetry (σ h ) and reduced symmetry of the arbitrary k -point, enforce the persistent spin textures (PST) to occur in full BZ. We induce the Rashba splitting by breaking the σ h through an out-of-plane external electric field (EEF). The inversion asymmetric site point group of the W atom introduces the hidden spin polarization in centrosymmetric layered bulk counterparts. Low energy k.p models demonstrate that the PST along the M–K line is robust to EEF and layer thickness, making them suitable for applications in spintronics and valleytronics.