Chirality transfer, inversion symmetry breaking and spin-splitting in layered perovskites

The strongly spin-orbit coupled conduction bands of layered (so-called two-dimensional) organic-inorganic lead halide perovskites can show large spin splittings, suggesting the possibility of spin-selective transport and future spintronic applications. We here use high-precision, all-electron first-principles theory (FHI-aims code [1,2]) to show how chiral organic components, structural transfer of chirality, inversion asymmetry and spin splitting and spin texture in layered perovskites are quantitatively linked [3,4]. Crystalline layered perovskites can be synthesized as high-quality single crystals, leading to unit cell sizes of hundreds of atoms (over 1,000 atoms in simulations that include defects). We computationally address their structure and electronic properties by dispersion-corrected semilocal and hybrid DFT and an efficient treatment of spin-orbit coupling, benchmarked against a fully relativistic, quasi-four-component electronic structure method [5]. Our approach faithfully predicts the quantum-well character of complex layered perovskites. We then show how introducing a particular chiral molecule can distort the inorganic structure so as to create strong spin splitting in the conduction bands of the quantum well [3]. Based on a group of chiral organic-inorganic crystalline layered perovskites, we finally show that a particular bond angle difference in the structure can serve as a faithful predictor of conduction band spin splitting in this promising class of semiconductor materials [4].