Demagnetization field simulation in hexagonal magnetic materials via Fast Fourier Transform

Two-dimensional van der Waals (vdW) magnetic materials with hexagonal structures exhibit exceptional potential for spintronics applications due to their unique magnetic properties. However, the accurate atomistic simulation of the demagnetization field in large hexagonal systems remains a challenge, as traditional Fast Fourier Transform (FFT) methods are limited to orthogonal lattices. In this study, we present a novel preprocessing method for hexagonal lattices to allow efficient computation of long-range demagnetization field by FFT acceleration. Through Atomistic Spin Dynamics simulations on layered CrI${}_3$, we reveal the significant impact of the demagnetization field on non-collinear spin textures, including the formation of Néel domain walls and the stability of spin vortices. This work provides new insights into the complex magnetic dynamics of 2D vdW materials at the atomistic scale.