Multiferroic properties of oxygen functionalized magnetic i-MXene

TL;DR

This study predicts a new 2D multiferroic material, i-MXene, with robust ferroelectricity and tunable magnetic properties, demonstrating a novel magnetoelectric coupling mechanism based on density functional theory calculations.

Contribution

It introduces a new 2D multiferroic i-MXene with intrinsic magnetoelectric coupling and tunable magnetic transition temperature, expanding the search for functional 2D multiferroics.

Findings

Predicted i-MXene as a stable 2D multiferroic with switchable polarization.

Identified a magnetoelectric coupling mechanism magnified by exchange frustration.

Demonstrated potential for room-temperature multiferroic applications.

Abstract

Two dimensional multiferroics inherit prominent physical properties from both low dimensional materials and magnetoelectric materials, and can go beyond their three dimensional counterparts for their unique structures. Here, based on density functional theory calculations, a MXene derivative, i.e., i-MXene (Ta$_{2/3}$Fe$_{1/3}$)$_2$CO$_2$, is predicted to be a type-I multiferroic material. Originated from the reliable $5d^0$ rule, its ferroelectricity is robust, with a moderate polarization up to $\sim12.33$ $\mu$C/cm$^2$ along the a-axis, which can be easily switched and may persist above room temperature. Its magnetic ground state is layered antiferromagnetism. Although it is a type-I multiferroic material, its N\'eel temperature can be significantly tuned by the paraelectric-ferroelectric transition, manifesting a kind of intrinsic magnetoelectric coupling. Such magnetoelectric effect is originated from the conventional magnetostriction, but unexpectedly magnified by the exchange frustration. Our work not only reveals a nontrivial magnetoelectric mechanism, but also provides a strategy to search for more multiferroics in the two dimensional limit.