Fermi-Level Interstitial Electron Contributions: A Key Mechanism Driving Magnetism in Electrides

Electrides, a unique class of ionic materials, are distinguished by their exceptional properties, such as low work functions, making them highly versatile for a broad range of applications. Remarkably, some electrides exhibit magnetism, even in the absence of conventional magnetic elements. However, the underlying mechanisms governing their magnetic properties require further investigation, which will enable the development of magnetic electrides that are not primarily limited to modifying materials with magnetic elements. In this study, we demonstrate that the proportion of interstitial electrons contributing to states near the Fermi level is a critical factor in the emergence of magnetism in electrides. Leveraging this insight, we successfully designed and identified a series of magnetic electrides, including Ca₃YNbSi₃ and Sr₂₄P₁₅F, without reliance on known magnetic prototypes. This strategy and the accompanying theoretical framework present a flexible and powerful approach, potentially expanding the frontiers of magnetic electrides research.