Magnetic frustration and non-collinear textures in layered Gd magnets

Abstract

Using scale-bridging simulations based on electronic structure theory and atomistic spin dynamics, we investigate the magnetic properties of skyrmionic GdRu$_2$Si$_2$ and GdRu$_2$Ge$_2$ layered rare-earth magnets and similar Gd-based compounds (GdAu$_2$Si$_2$, GdAu$_2$Ge$_2$, GdAg$_2$Si$_2$ and GdAg$_2$Ge$_2$). By studying the trends across this structural family, we confirm the importance of magnetic frustration and dipolar interactions for the stability of non-collinear and skyrmion phases. Furthermore, our calculations predict promising opportunities for chemical tuning of these magnets in terms of the balance between various exchange interactions and the character of the magnetic anisotropy. These changes lead to the formation of new types of skyrmions that are stable in a wide range of applied external magnetic field. In particular, we propose partial alkali-metal substitution of Gd in GdRu$_2$Si$_2$ leading to GdKRu$_4$Si$_4$, GdRbRu$_4$Si$_4$, GdCsRu$_4$Si$_4$ as well as GdYRu$_4$Si$_4$ compounds, and suggest that it is likely to result in an ordered layered structure, similarly to previously reported iron pnictides like CaKFe$_4$As$_4$.