A polar rotor for designing antiferroelectricity–antiferromagnetism in a quasi-2D organic–inorganic hybrid perovskite

Abstract

Antiferroelectric–antiferromagnetic (AFE–AFM) multiferroic materials have received extensive attention due to their applications in high-energy storage devices. However, achieving AFE–AFM properties in a hybrid molecular material is particularly challenging, because electric dipole orders and magnetic dipole orders are often mutually exclusive. Here, we report a molecular strategy that utilizes polar rotors combined with magnetic modules to overcome the above exclusion in a quasi-two-dimensional (Q-2D) hybrid perovskite platform. Based on non-ferroic [CBA]₂CoCl₄ (CBA = cyclobutylaminium, CBC), F-substituted [DFCBA]₂CoCl₄ (DFCBA = 3,3-difluorocyclobutylamine, DFCBC) with polar rotors shows AFE–AFM properties. Systematic experimental results reveal that the freezing of rotor movement forms antiparallel arranged dipole arrays, which is the origin of the AFE feature. Moreover, DFCBC exhibits antiferromagnetism from the inorganic [CoCl₄]²⁻ component, reaching 1.73Nβ at 50 kOe. Our study presents the advantages of the Ruddlesden–Popper (RP) hybrid perovskite molecular rotor platform for realizing AFE–AFM properties. It gives insight into the molecular design for controlling the macroscopic physical properties.