Magnetic resonance probing of ferroelectricity and magnetism in metal-organic frameworks

TL;DR

This study uses electron paramagnetic resonance to investigate ferroelectric and magnetic properties in metal-organic frameworks, revealing the absence of magnetoelectric coupling at the ferroelectric transition but detecting it at the antiferromagnetic transition.

Contribution

It demonstrates the application of EPR to probe ferroelectricity and magnetism in MOFs, providing new insights into their coupling mechanisms and the influence of cations on crystal fields.

Findings

No magnetoelectric coupling at ferroelectric transition.

Detection of magnetoelectric coupling at antiferromagnetic transition.

Crystal field mainly influenced by DMA+ cations.

Abstract

We employ electron paramagnetic resonance (EPR) of the spin probe Mn2+ to study the paraelectric ferroelectric transition in DMAMnF and Mn2 doped DMZnF, which are considered to be model metal organic frameworks (MOF) with a Pb free perovskite architecture. In DMAMnF, we study the variation of the Mn2+ EPR line shape and intensity at the X-band (9.4 GHz) and over 80 to 300 K, and we show the absence of magnetoelectric coupling at the ferroelectric transition. At the antiferromagnetic transition in DMMnF, we detect a magnetoelectric coupling caused by weak ferromagnetism in the AFM phase. In DMZnF, the combination of EPR of the Mn2+ probe and DFT show that the crystal field is predominantly determined by the DMA+ cations.