Molecular modification in hybrid materials induces multiple ferroic ordering

Abstract

Multiferroic materials are substances exhibiting multiple ferroic order parameters within a single phase. They hold immense potential for applications in high-density data storage and energy conversion. However, the inherent contradiction between the electronic structure requirements of ferroelectricity and ferromagnetism, coupled with the stringent symmetry changes demanded by ferroelectricity and ferroelasticity, has resulted in a scarcity of multiferroic materials exhibiting all three ferroic characteristics within a single phase. This work designed and synthesized a novel molecular multiferroic compound [N(CH₃)₃(CH₂CClCH₂)][FeBr₄] (CTPAM-FeBr₄) through multiple modifications of TPM-FeBr₄. By introducing an unsaturated bond in the organic moiety to induce phase transitions for ferroelectricity and ferroelasticity, followed by halogen substitution to suppress low-temperature phase transitions via halogen interactions, the compound achieves the coexistence of ferroelectricity, ferroelasticity, and antiferromagnetism within a single phase. This provides a novel strategy for developing molecular multiferroic materials with multiple coexisting ferroic orders.