Trio of ternary MAX phases expand possibilities for 2D ferromagnetic materials fabrication

Two-dimensional ferromagnetic materials have potential applications in magnetics, including spintronics and storage devices. MAX phases are a family of nanolaminated ternary carbides or nitrides.

In MAX phases, if the layers of the A element in their chemical formula, represented by M_n+1AX_n, are magnetic, their weak interaction with the nearest M atoms make the MAX phase an ideal template for constructing 2D ferromagnetic monolayers. However, none of the more than 80 ternary MAX phases reported have exclusively magnetic elements occupying the A sites.

Li et al. synthesized three ternary MAX phases with the magnetic element iron exclusively occupying the A layers. They produced Ta₂FeC, Ti₂FeN, and Nb₂FeC through isomorphous replacement of the A element with iron, which forms 2D single-atom-thick iron layers.

The authors found two of the fabricated MAX phases exhibited ferromagnetic behavior when near room temperature. Theoretical calculations revealed the magnetism is mainly due to intralayer exchange interaction of the constructed 2D iron atomic layers.

The authors believe the variety in structure and composition of MAX phases offers researchers the opportunity to tune the magnetic properties of single-atom-thick 2D layers by changing the elements in the layers to exhibit different properties for different applications, such as catalysis, energy storage, and electromagnetic interference.

“This work suggests a new approach to make 2D ferromagnetic monolayers,” said author Qing Huang. “Since MAX phases are well-known structural ceramics with outstanding high temperature performance, the 2D ferromagnetic and functional monolayers in them will be much robust and stable when compared with other 2D films.”

Source: “Near-room temperature ferromagnetic behavior of single-atom-thick 2D iron in nanolaminated ternary MAX phases,” by Youbing Li, Jinghua Liang, Haoming Ding, Jun Lu, Xulin Mu, Pengfei Yan, Xiao Zhang, Ke Chen, Mian Li, Per O. Å. Persson, Lars Hultman, Per Eklund, Shiyu Du, Hongxin Yang, Zhifang Chai, and Qing Huang, Applied Physics Reviews (2021). The article can be accessed at https://aip.scitation.org/doi/full/10.1063/5.0059078 .