Ferroelectric Chirality‐Driven Direction‐Tunable and Spin‐Invertible Corner States in 2D MOF‐Based Magnetic Second‐Order Topological Insulators

Abstract Despite the rapid progress in predicting 2D magnetic second‐order topological insulators (SOTIs), effective strategies for manipulating their spin‐polarized corner states remain largely unexplored. The interplay between ferroelectricity, chirality, magnetism, and topology presents an untapped opportunity for controlling these corner states. Here, a novel approach for tuning spin‐polarized corner states in 2D magnetic SOTIs is proposed by inducing ferroelectric chirality in 2D metal–organic frameworks (MOFs) with intrinsic structural flexibility. Through symmetry analysis, pyrazine (pyz) ligands are strategically replaced with 2‐pyrazinolate (2‐pyzol) ligands in the 2D MOF Cr(pyz) 2 , leading to the emergence of a new 2D magnetic SOTI, Cr(2‐pyzol) 2 , which facilitates ferroelectric chirality controlled spin‐polarized corner states in both spin channels. Through first‐principle calculations, it is demonstrated that Cr(2‐pyzol) 2 belongs to ferroelectric chiral systems, and its corner states can be directionally tuned in real space and spin‐inverted in spin space upon ferroelectric chirality switching. This work represents the first attempt to simultaneously manipulate corner states in both real space and spin space, offering a new strategy for integrating ferroelectric chirality into 2D MOF‐based magnetic SOTIs.