  Spin-orbit coupling (SOC) combined with broken inversion symmetry play key
roles in inducing Rashba effect. The combined spontaneous polarization and
Rashba effect enable controlling a material's spin degrees of freedom
electrically. In this work we investigated the electronic band structure for
several combinations of TiX2 monolayers (X= Te, S and Se): TiTe2/TiSe2,
TiTe2/TiS2, and TiSe2/TiS2. Based on the observed orbital hybridization between
the different monolayers in these hetero-structures (HSs), we conclude that the
most significant Rashba splitting occurs in TiSe2/TiS2. Subsequently, we used
Fluorine (F) as an adatom over the surface of TiSe2/TiS2 at hollow and top
sites of the surface to enhance the Rashba intensity, as the F adatom induces
polarization due to difference in charge distribution. Furthermore, by
increasing the number of F atoms on the surface, we reinforced the band
splitting, i.e., we observe Rashba splitting accompanied by Zeeman splitting at
the valence-band edge states. Berry curvatures at K and K' with equal and
opposite nature confirms the existence of valley polarization. The
computationally observed properties suggest that these HSs are promising
candidates for spin-valley Hall effect devices and other spintronic
applications.
