Layered Iron Oxyhydroxide Hosting Quantum Magnetism and Chirality

Particle assembly is now recognized as a new toolbox capable of controlling the thermodynamic and kinetic pathways of nanocrystal formation. During the crystallization process of iron oxide, particle attachment growth mechanisms are frequently observed, rendering the conventional nucleation and growth theories—based on ion accretion—insufficient for explaining phenomena such as the selection of intermediate polymorphism, complex morphogenesis, and the formation of oriented nanocrystalline structures. Engineering the coordination between surface ligands and metal ligands can be a versatile approach to fine-tuning the atomic topography of nanomaterials and their relevant spin ordering. However, the role of surface ligands in the crystallization of metal oxides remains underexplored.<br/>Here, we found that surface ligand incorporation during the crystallization of iron oxide produces a previously unknown two-dimensional (2D) iron oxyhydroxide that can host a low-dimensional quantum spin system. The organic ligands coordinating with iron atoms during crystallization induce an unexpected zig-zag stacking of dimerized FeO octahedra, leading to a layered crystal structure with significantly enlarged interlayer spacing. This study elucidate how the low dimensionality of this crystal can support low dimentional antiferromagnetism with a quantum spin ladder model. The surface ligand incorporation process is universal for various types of ligands, which can induce a transition from achiral to chiral crystallographic symmetry after the intercalation of enantiomeric amino acids, resulting in chiroptically active iron oxyhydroxide. Both achiral and chiral iron oxyhydroxides exhibit quantum magnetism, with a portion of spins being excitable into parallel arrangements even under low external magnetic fields at room temperature. Thus, chiral iron oxyhydroxide facilitates the control of spin-polarized photon absorption by combining quantum magnetism with crystallographic chirality. This result will provide a versatile crystallization control strategy to explore various families of inorganic-organic hybrids with new functionalities.