Non-coplanar spin structure in Co_1/3TaS₂ induced by the biquadratic spin interaction

Recently, antiferromagnetic materials with nontrivial spin arrangements have gained broad interest due to their unique properties, making them suitable for technological applications. In Co_1/3TaS₂, a large spontaneous Hall effect induced by a non-coplanar spin structure, as well as a two-step phase transition of the spin structure with respect to temperature, has been experimentally reported [1,2,3]. The biquadratic (BQ) spin interaction is suggested as the mechanism stabilizing the non-coplanar structure. A phenomenological model confirms that, while tiny compared to the bilinear interaction, finite BQ interactions are necessary to explain the experimental results.

We employ the SCE-DLM method to calculate the BQ interaction from first principles without bias [4,5]. The results of SCE-DLM are consistent with both experiments and the phenomenological model. In the presentation, we will discuss these results in further detail.