Engineering Spin Textures in 2D Hybrid Perovskites

The crystalline symmetry plays a key role in determining the spin properties of charge carriers in solid-state structures that are required for realizing spin-optoelectronic effects.[1-4] In 2D organic-inorganic perovskites (2D-OIPs) with alternating layers of organic cations (A) and metal-halide octahedra ([BX₆]^4- ; B = Pb, Sn and X = Cl, Br, I), the structural symmetry and optoelectronic properties can be tailored by the non-covalent interactions.[5-10] Here, we show how organic ammonium cations with restricted rotational motions can introduce asymmetric polar distortion modes in the B – X layers. The inherent polarization modifies the local effective magnetic fields through the spin-orbit coupling effect, driving the momentum-dependent spin polarizations (spin textures) at the frontier electronic bands of the 2D-OIPs. To rationalize these spin textures, we developed an analytical model that quantifies the effect of the inter-layer coupling on spin properties in multi-quantum-well structures. The obtained correlation between the spin textures (simulated through first-principles calculations) in a set of 2D-OIPs with different symmetry elements and the non-covalent interactions that are responsible for those symmetry elements (analyzed from single crystal X-ray diffraction measurements) directs us toward a design strategy for obtaining 2D-OIP semiconductors with tunable band gaps and measurable spin-properties (e.g., spin splitting, spin lifetime, and spin localization) that are suitable for room-temperature spin-optoelectronic applications. <br/> <br/>1.Kepenekian, M. and Even, J. (2017) <i>J. Phys. Chem. Lett.</i> 8, 3362-3370.<br/>2.Tao, L.L. and Tsymbal, E.Y. (2018) <i>Nat. Commun.</i> 9, 2763.<br/>3.Wang, J.<i> et al.</i> (2019) <i>Nat. Commun.</i> 10, 129.<br/>4.Lu, H.<i> et al.</i> (2022) <i>Nat Rev Chem</i> 6, 470-485.<br/>5.Saparov, B. and Mitzi, D.B. (2016) <i>Chem. Rev.</i> 116, 4558-4596.<br/>6.Liu, C.<i> et al.</i> (2018) <i>Phys. Rev. Lett.</i> 121, 146401.<br/>7.Chakraborty, R.<i> et al.</i> (2021) <i>Chem. Mater.</i> 34, 288-296.<br/>8.Jana, M.K.<i> et al.</i> (2021) <i>Nat. Commun.</i> 12, 4982.<br/>9.Zhang, L.<i> et al.</i> (2022) <i>Nat. Photon.</i> 16, 529-537.<br/>10.Chakraborty, R.<i> et al.</i> (2023) <i>J. Am. Chem. Soc.</i> 145, 1378-1388.