Tuning a sign of magnetoelectric coupling in paramagnetic NH2(CH3)2Al1-xCrx(SO4)*6H2O crystals by metal ion substitution

TL;DR

This study demonstrates how metal-ion substitution in paramagnetic ferroelectric crystals can induce and tune magnetoelectric interactions, including sign reversal, with significant implications for designing ME coupling in hybrid materials.

Contribution

It reveals the ability to control and reverse the sign of magnetoelectric coupling through Cr ion substitution in DMAAS crystals, a novel approach in ME material engineering.

Findings

Cr substitution induces paramagnetism in DMAAS crystals.

The ferroelectric transition temperature shifts nonlinearly with Cr content.

The ME coupling coefficient reaches 1.7 ns/m, among the highest reported.

Abstract

Hybrid organometallic systems offer a wide range of functionalities, including magnetoelectric interactions. However, the ability to design on-demand ME coupling remains challenging despite a variety of host-guest configurations and ME phases coexistence possibilities. Here, we report the effect of metal-ion substitution on the magnetic and electric properties in the paramagnetic ferroelectric DMAAS crystals. Doing so we are able to induce and even tune a sign of the ME interactions in the paramagnetic ferroelectric state. Both studied samples with 6.5% and 20% of Cr become paramagnetic, contrary to the initial diamagnetic compound. Due to the isomorphous substitution with Cr the ferroelectric phase transition temperature increases nonlinearly, with the shift being larger for the sample with Cr content of 6.5%. A magnetic field applied along the polar c axis increases ferroelectricity for this sample and shifts Tc to higher values, while inverse effects are observed for sample containing 20% of Cr. The ME coupling coefficient of 1.7ns/m found for a crystal with 20% of Cr is among the highest reported up to now. The observed sign change of ME coupling coefficient with a small change in Cr content paves the way for ME coupling engineering.