Near-room temperature ferromagnetic behavior of single-atom-thick 2D iron in nanolaminated ternary MAX phases Available to Purchase

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.