Chemical Control of Optical Band Gap and Magnetic Properties in Fe-Alloyed Na–In Halide Layered Perovskites

The recent breakthroughs in understanding the unique physics of two-dimensional (2D) magnetic materials have ignited the exploration of new types of layered magnetic semiconductors. In contrast to conventional inorganic 2D van der Waals crystals, hybrid organic–inorganic layered perovskite frameworks provide better chemical and structural versatility. These frameworks allow for easy modulation of their structural, optical, electronic, and magnetic properties through variation of both organic and inorganic components. Here, we report the Fe-alloyed Na–In 2D layered double perovskite with a phenylethylammonium (PEA) cation as the organic spacer. Powder X-ray diffraction (PXRD) patterns of these alloyed materials show that the d -spacing of various planes changes differently with Fe 3+ alloying. UV–vis absorption spectra depict that their optical band gap is highly tunable with the Fe 3+ amount. Magnetic susceptibility measurements indicate an antiferromagnetic (AFM) coupling in these alloyed materials. The values of the Curie constant ( C ), Curie–Weiss temperature (θ CW ), and lower bound value of geometrical frustration factors are highly dependent on the amount of Fe 3+ alloying in these layered double perovskites (LDPs). Our research illustrates the abundant and fascinating magnetic properties found in these transition-metal-alloyed LDPs, thereby opening avenues for the development of multifunctional magnetic materials.