M_n+1AX_n (MAX) phases' nanolaminated ternary carbides or nitrides possess a unique crystal structure in which single-atom-thick “A” sublayers are interleaved by alternative stacking of a “M_n+1X_n” sublayer; these materials have been investigated as promising high-safety structural materials for industrial applications because of their laminated structure and metal and ceramic properties. However, limited of A-site elements in the definition of M_n+1AX_n phases, it is a huge challenge for designing nanolaminated ferromagnetic materials with single-atom-thick two-dimensional iron layers occupying the A layers in the M_n+1AX_n phases. Here, we report three new ternary magnetic M_n+1AX_n phases (Ta₂FeC, Ti₂FeN, and Nb₂FeC) with A sublayers of single-atom-thick two-dimensional iron through an isomorphous replacement reaction of M_n+1AX_n precursors (Ta₂AlC, Ti₂AlN, and Nb₂AlC) with a Lewis acid salts (FeCl₂). All these M_n+1AX_n phases exhibit ferromagnetic behavior. The Curie temperatures of the Ta₂FeC and Nb₂FeC M_n+1AX_n phases are 281 and 291 K, respectively, i.e., close to room temperature. The saturation magnetization of these ternary magnetic MAX phases is almost two orders of magnitude higher than V₂(Sn,Fe)C, whose A-site is partially substituted by Fe. Theoretical calculations on magnetic orderings of spin moments of Fe atoms in these nanolaminated magnetic M_n+1AX_n phases reveal that the magnetism can be mainly ascribed to an intralayer exchange interaction of the two-dimensional Fe atomic layers. Owing to the richness in composition of M_n+1AX_n phases, our work provides a large imaginary space for constructing functional single-atom-thick two-dimensional layers in materials using these nanolaminated templates.

中文翻译：

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纳米层压三元 MAX 相中单原子厚二维铁的近室温铁磁行为

Mn _{+ 1} AX _n (MAX) 相的纳米层压三元碳化物或氮化物具有独特的晶体结构，其中单原子厚的“A”子层通过交替堆叠“Mn _{+ 1} X _n ”子层而交错；由于这些材料的层压结构以及金属和陶瓷特性，这些材料已被研究为用于工业应用的有前途的高安全性结构材料。然而，由于 M _{n+ 1} AX _n相定义中 A 位元素的限制，设计具有单原子厚二维铁层的纳米层压铁磁材料是一个巨大的挑战，它占据了 M _{n+ 1 中}的 A 层。AX _n相。在这里，我们报告了三个新的三元磁性 M _{n+ 1} AX _n相（Ta ₂ FeC、Ti ₂ FeN 和 Nb ₂ FeC），通过 M _{n+ 1}的同晶置换反应，具有单原子厚二维铁的 A 亚层AX _n前体（Ta ₂ AlC、Ti ₂ AlN 和 Nb ₂ AlC）与路易斯酸盐（FeCl ₂）。所有这些 M _{n+ 1} AX _n相都表现出铁磁行为。Ta ₂ FeC 和 Nb ₂ FeC M的居里温度_{n+ 1} AX _n相分别为281 和291 K，即接近室温。这些三元磁性 MAX 相的饱和磁化强度几乎比 V ₂ (Sn,Fe)C高两个数量级，V ₂ (Sn,Fe)C 的 A 位部分被 Fe 取代。对这些纳米层压磁性 M _{n+ 1} AX _n相中Fe 原子自旋矩的磁性排序的理论计算表明，磁性主要归因于二维 Fe 原子层的层内交换相互作用。由于 M _{n+ 1} AX _{n 的}成分丰富 阶段，我们的工作为使用这些纳米层压模板在材料中构建功能性单原子厚二维层提供了一个大的想象空间。