Ferroelasticity, thermochromism, semi-conductivity, and ferromagnetism in a new layered perovskite: (4-fluorophenethylaminium)2[CuCl4]

Abstract

Organic–inorganic layered perovskites exhibit many exotic properties benefiting from their relatively soft lattices and quantum-well structures, thus attracting increasing attention in the field of sensors, signal processing, and memory devices. Herein, we present a new layered perovskite, (4-fluorophenethylaminium)₂[CuCl₄], which shows above-room-temperature ferroelasticity, reversible thermochromism, indirect semi-conductivity, and low-temperature ferromagnetic ordering. Specifically, this compound undergoes an order–disorder phase transition at 348/340 K and an mmmF2/m ferroelastic phase transition at 393/390 K with a spontaneous strain of 0.011. Upon heating from 298 to 415 K, the variation in inorganic coordination geometry, together with the order–disorder transition of organic cations, endows this compound with a reversible colour change from yellowish to red-brown and a conductivity enhancement by more than three orders of magnitude. The intra-layer ferromagnetic exchange interactions result in ferromagnetic ordering at below 8.8 K. The studies on this hybrid layered perovskite with multiple physical channels are of great significance for seeking novel hybrid crystals in the field of multiple information processing and encryption.