Stereochemically Active Lone Pair Effect of Cations Triggers Giant Rashba-Dresselhaus Spin Splitting in Ferroelectric Semiconductors for Circularly Polarized Light Detection.
basic_science · Level V
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- Record sourced from PubMed, PMID 41735779.
- Also identified by DOI 10.1002/adma.202519568.
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Abstract
Rashba-Dresselhaus (RD) spin splitting arising from spin-orbit coupling in spatial inversion asymmetric semiconductors is critical for realizing numerous advanced spintronic applications. However, modulating the RD spin splitting coefficient (α<sub>RD</sub>) is challenging due to the unclear structural-property relationship. Herein, inspired by highly distorted inorganic selenites containing stereochemically active lone pair (SCALP) electrons, we selected 4-aminomorpholine cation (4AM) containing SCALP electrons to synthesize a new two-dimensional (2D) ferroelectric semiconductor (4AM)<sub>2</sub>PbBr<sub>4</sub>, exhibiting a giant α<sub>RD</sub> of 2.377 eV Å with ΔE<sub>RD</sub> = 126 meV and Δk<sub>0</sub> = 0.106 Å<sup>-1</sup> that differentiates circularly polarized light-excited carriers in the momentum space via spin-dependent optical transition selection rules with an asymmetric factor of 0.65. A geometric structure-property relationship study reveals that incorporating SCALP into the organic cations enhances their net polarity and induces substantial distortions within the inorganic sublattices that enhance the α<sub>RD</sub>. This work reveals the regulatory mechanism of organic cations on distortion of inorganic octahedron and provides a new approach for efficient synthesis and rapid screening of 2D ferroelectric semiconductors with large α<sub>RD</sub>.