Ferroelectric Rashba cofunctionality in [CH₃PH₃]SnBr₃

Ferroelectric materials exhibit spontaneous polarization, which is reversible by the application external electric field. A few ferroelectrics exhibit spin splitting due to spin-orbit coupling, with values ranging from 0.1 meV to 4 eV. Such spin-splitting gives origin to spin-textures, which in ferroelectrics may couple to the direction of electric polarization giving origin to ferroelectricity Rashba effects co-functionality, which is of great importance for potential applications. We use first-principles density functional theory computations to predict Rashba effects cofunctional with ferroelectricity in a recently synthesized lead-free hybrid organic-inorganic perovskite MPSnBr3 (MP = methylphosphonium, ( [CH₃PH₃] ⁺)). The ground state of the material is polar monoclinic with calculated spontaneous polarization of 3.01 µC/cm². It exhibits near band edges spin-splitting of up to 3.3 meV and Rashba coefficient up to 0.62 eV Å. The spin textures have different topologies in the conduction and valence bands, which originates from the difference in the spin-momentum coupling strengths. Our study reveals the potential of MPSnBr3 for low-temperature applications in spintronics and quantum computing.