Two-dimensional multiferroics inherit prominent physical properties from both low-dimensional materials and magnetoelectric materials, and they surpass their three-dimensional counterparts for their unique structures. Here, based on density functional theory calculations, a MXene derivative, i.e., i-MXene $({\mathrm{Ta}}_{2/3}{\mathrm{Fe}}_{1/3}{)}_2{\mathrm{CO}}_2$, is predicted to be a type-I multiferroic material. Originating from the reliable $5d^0$ rule, its ferroelectricity is robust, with a moderate polarization up to $\sim 12.33\mu \mathrm{C}/{\mathrm{cm}}^2$ 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 Néel temperature can be significantly tuned by the paraelectric-ferroelectric transition, manifesting a kind of intrinsic magnetoelectric coupling. Such a magnetoelectric effect originates from the conventional magnetostriction, but it is unexpectedly magnified by the exchange frustration. Our work not only reveals a nontrivial magnetoelectric mechanism, but it also provides a strategy to search for more multiferroics in the two-dimensional limit.

中文翻译：

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氧功能化磁性i-MXene的多铁性

二维多铁性材料继承了低维材料和磁电材料的突出物理特性，并且因其独特的结构而超越了三维多铁性材料。这里，基于密度泛函理论计算，MXene 衍生物，即 i-MXene$({塔}_{2/3}{铁}_{1/3}{)}_2{\mathrm{二氧化碳}}_2$, 预计为 I 型多铁性材料。源于可靠$5d^0$ 规则，它的铁电性很强，中等极化可达 $～12.33\mu \mathrm{C}/{\mathrm{厘米}}^2$ 沿着 $\mathrm{一种}$-轴，可以轻松切换，并且可以持续高于室温。它的磁性基态是层状反铁磁性。虽然它是一种 I 型多铁性材料，但其 Néel 温度可以通过顺电-铁电转变进行显着调节，表现出一种固有的磁电耦合。这种磁电效应源于传统的磁致伸缩，但意外地被交换受挫放大了。我们的工作不仅揭示了一个重要的磁电机制，而且还提供了一种在二维极限中寻找更多多铁性的策略。