Elucidation of dipolar dynamics and the nature of structural phases in the [(CH3)2NH2][Zn(HCOO)3] hybrid perovskite framework

Abstract

The indications of peculiar multiferroic behavior of dimethylammonium metal-formate perovskite frameworks raised important questions about the origin of the structural phase transition, structural phases and dipolar dynamics in these compounds. Here we provide answers on some of these phenomena by presenting a comprehensive experimental and theoretical study of the [(CH₃)₂NH₂][Zn(HCOO)₃] framework. Broadband dielectric spectroscopy assisted by molecular dynamics simulations allows us to probe the dipolar relaxation dynamics in both structural phases on an extensive time scale. The results of dielectric spectroscopy are complemented by non-linear dielectric susceptibility, electric field dependent and ultrasonic experiments. Contrary to a prevailing notion, we clearly demonstrate that the [(CH₃)₂NH₂][Zn(HCOO)₃] perovskite is not a relaxor material and raise serious doubts about its proper ferroelectric nature.