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 Fe3+ alloying. UV–vis absorption spectra depict that their optical
band gap is highly tunable with the Fe3+ amount. Magnetic
susceptibility measurements indicate an antiferromagnetic (AFM) coupling
in these alloyed materials. The values of the Curie constant (C), Curie–Weiss temperature (θCW), and lower bound value of geometrical frustration factors are highly
dependent on the amount of Fe3+ 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.