Chemical Control of Magnetic Ordering in Hybrid Fe-CI Layered Double Perovskites

Recent discoveries of novel physics in two-dimensional (2D) magnetic materials have sparked the search of new layered magnetic semiconductors. Compared to the traditional inorganic 2D van der Waals crystals, hybrid organic-inorganic metal-halide frameworks offer significantly enhanced chemical and structural versatility, where their optical, electronic, and magnetic properties can be readily modulated with both organic and inorganic components. Here, we reported a series of new Fe-Cl-based layered double perovskites (LnMMCl8)-M-I-Cl-III, [n = 4, L = phenylethylammonium or chiral R-(+)-beta-methylphenethylammonium and n = 2, L = 1,4-butanediammonium; M-I = Ag/Na; M-III = Fe/In]. UV-vis measurements show that their optical band gaps are highly tunable by varying the organic cations, M-I ion, and M-III ion. Magnetic susceptibility measurements suggest an antiferromagnetic coupling between the nearest Fe-III-Fe-III where the Curie-Weiss temperature, Neel temperature, and frustration factors can be easily modulated with their compositions and dimensionality. Our study demonstrates the rich and interesting magnetic properties in these layered transition-metal-halide double perovskites and paves the way for design of multifunctional magnetic materials.