Fig. 6: Rashba band splitting shown in exfoliated RPPs of n > 1.
From: Unlocking surface octahedral tilt in two-dimensional Ruddlesden-Popper perovskites
a, b Varying configurations of the top BA molecule and N–H···I hydrogen bond between BA and inorganic cage in surface of monolayer n = 1 (a) and n = 4 (b). c Schematic band diagram showing the bands shifted in k-space by k0. An indirect band gap is displayed with an energy ΔE below the direct band gap. d High symmetry points of the Brillouin zone in n = 2 RPP structure. e Dispersed band structures of monolayer n = 2 RPP along X–Γ–Y directions, showing the Rashba band splitting feature. Inset, asymmetric structure of monolayer n = 2 RPP with enhanced surface octahedral tilt. f Spin-textures of valance bands projected on the 2D X–Y plane near Γ point, where the inner and outer bands have anti-clockwise and clockwise in-plane spin-textures, respectively. The color code represents the Sz spin component. g Simulated band structure of monolayer n = 1 RPP along X–Γ–Y direction showing no Rashba splitting. Inset, centrosymmetric structure of monolayer n = 1 RPP without obvious octahedral tilt.
