Chemically and electrically tunable spin polarization in ferroelectric Cd-based hybrid organic-inorganic perovskites

Density functional theory computations are used to predict the electronic structure of Cd-based hybrid organic-inorganic high-${T}_C$ ferroelectric perovskites with TMCM-${\mathrm{CdCl}}₃$ being one representative. We report Rashba-Dresselhaus spin splitting in the valence band of these nonmagnetic compounds. Interestingly, we find in computations that the splitting is not necessarily sensitive to the polarization of the material but to the organic molecule itself which opens a way to its chemical tunability through the choice of the molecule. Further chemical tunability of spin splitting is shown to be possible through a substitution of Cl in the ${\mathrm{CdCl}}₃$ chains as the valence band was found to originate from Cl-Cl weekly bonding orbitals. For example, the substitution of Cl with Br in TMCM-${\mathrm{CdCl}}₃$ resulted in a ten times increase of spin splitting. Furthermore, the spin polarization in these materials gives origin to persistent spin textures which are coupled to the polarization direction, and, therefore, can be controlled by the electric field. This is promising for spintronics applications.