Ferroelasticity and Canted Antiferromagnetism in Two-Dimensional Organic–Inorganic Layered Perovskite [C₆H₉(CH₂)₂NH₃]₂FeCl₄

Two-dimensional organic-inorganic perovskites have been attracted as candidates for multiferroic materials that exhibit two or more ferroic orders such as ferromagnetism, ferroelectricity, ferroelasticity, and ferrotoroidicity. Here, we introduce the structure, ferroelastic domains and magnetic properties of the two-dimensional organic-inorganic perovskite [C₆H₉(CH₂)₂NH₃]₂FeCl₄ (CHEA-Fe) composed of 2-(1-cyclohexenyl)ethylammonium and FeCl₄ ^2-. CHEA-Fe underwent two ferroelastic phase transitions from tetragonal to orthorhombic at 332 K and to monoclinic at 232 K with decreasing temperature and exhibited ferroelastic domains under polarized light as a consequence of these ferroelastic phase transitions. Magnetization measurements exhibited two magnetization jumps at the transition temperature, which agrees with ferroelastic phase transitions. Furthermore, CHEA-Fe acted as canted antiferromagnetism below <i>T</i> _N = 85.7 K. The isothermal magnetization revealed a magnetic hysteresis when the magnetic field was applied along the stacking axis of the layers.