Ferroelectricity and magnetism in metal-formate frameworks of [NH4][M(HCOO)3] (M = Sc to Zn): a first-principles study

Abstract

A comprehensive study on the ferroelectricity and magnetic properties of metal-formate frameworks [NH₄][M(HCOO)₃] (M = 3d transition metal atom) (metal-MFF) is performed based on first-principles calculations. Our results show that a paraelectric–ferroelectric phase transition in metal-MFF is triggered by the disorder–order transition of NH₄⁺ cations. Their ferroelectric polarization can be tuned by metal ions in the framework, ranging from 2.17 to 3.17 μC cm⁻². Except for Zn-MFF, all metal-MFF are magnetic semiconductors, where Sc- and Cr-MFF are ferromagnetic and others are antiferromagnetic in their ground states. In particular, the antiferromagnetic semiconductor to ferromagnetic half metal transition can be obtained in metal-MFF with either electron or hole doping.