Systematic search for two-dimensional ferromagnetic materials

We perform a systematic materials informatics search for two-dimensional (2D) ferromagnetic materials (2DFM) in the Inorganic Crystal Structure Database (ICSD). The key indicator in the search is that the candidates have a 2D network composed of magnetic atoms and heavy atoms. From the 187,093 entries in the ICSD, the search identified 15 candidates whose magnetic order are then determined by first-principles calculations and Curie temperatures obtained by either analytical solution or Monte Carlo simulation of the 2D Ising model. For the 15 candidates, eight materials have ferromagnetic order including three known structural prototypes and the two 2DFM materials discovered in recent experiments. More importantly, the search produced two new structural prototypes and a very promising material, ${\mathrm{Cr}}_3{\mathrm{Te}}_4$, which has a calculated Curie temperature one order of magnitude higher than the others.

Figure 1

A schematic diagram to illustrate the search procedure for 2DFM materials.

Figure 2

Schematic diagram to illustrate the algorithm for determining the dimensionality of a given structure. In a $2\times 2$ supercell, the number of covalently connected atoms is one time, two times, and four times that of the unit cell, depending on the dimensionality of the structure.

Figure 3

The five structural prototypes of 2DFM materials obtained in this work. Blue spheres and gray spheres represent magnetic atoms and heavy atoms, respectively. The exchange interactions are marked by broken lines where black lines are for $J$ or $J_1$, orange for $J_2$, and red for $J_3$.