Antibonding and Electronic Instabilities in GdRu2X2 (X = Si, Ge, Sn): A New Pathway Toward Developing Centrosymmetric Skyrmion Materials

Abstract

Chemical bonding is key to unlocking the potential of magnetic materials for future information technology. Magnetic skyrmions are topologically protected nano-sized spin textures that can enable high-density, low-power spin-based electronics. Despite increasing interest in the discovery of new skyrmion hosts, the electronic origins of the skyrmion formation remain unknown. Here, we study GdRu₂X₂ (X = Si, Ge, Sn) as a model system to investigate the connection between chemical bonding, electronic instability, and the critical temperature and magnetic field at which skyrmions emerge. The nature of the electronic structure of GdRu2X2 is characterized by chemical bonding, Fermi surface analysis, and the density of energy function. As X-p orbitals become more extended from Si-3p to Ge-4p and Sn-5p, improved interactions between the Gd spins and the [Ru2X2] conduction layer, along with increased destabilizing energy contributions, are obtained. GdRu₂Si₂ possesses a Fermi surface nesting (FSN) vector [Q = (q, 0, 0)] r.l.u.; whereas GdRu₂Ge₂ displays two inequivalent FSN vectors [QA = (q, 0, 0); QB = (q, q, 0)] r.l.u., and GdRu2Sn2 features multiple Q vectors. In addition, competing ferromagnetic and antiferromagnetic exchange interactions in the Gd plane become more pronounced as a function of X. These results reveal a correlation among the electronic instability, the strength of competing magnetic interactions, and the temperature and magnetic field conditions under which skyrmions form. This work demonstrates how chemical bonding and electronic structure can enable a new framework for understanding and developing skyrmions under desired conditions that would otherwise be impossible.