Anionic Electron Dimensionality and Monolayer Ferromagnetism in Y-Co Electrides

Electrides, characterized by spatially confined anionic electrons, have emerged as a promising class of materials for catalysis, magnetism, and superconductivity. However, transition-metal-based electrides with diverse electron dimensionalities remain largely unexplored. Here, we perform a comprehensive first-principles investigation of Y-Co electrides, focusing on Y 3 Co, Y 3 Co 2 , and YCo. Our calculations reveal a striking dimensional evolution of anionic electrons: from two-dimensional (2D) confinement in YCo, to one-dimensional (1D) in Y 3 Co 2 , and zero-dimensional (0D) in Y 3 Co. Remarkably, the YCo monolayer exhibits intrinsic ferromagnetism with a magnetic moment of 0.65 μB per formula unit, driven by spin-polarized anionic electrons mediating long-range coupling between Y and Co ions. The monolayer also shows a low exfoliation energy (1.66 J/m 2 ), suggesting experimental feasibility. All three electrides feature low work functions (2.76-3.11 eV) and Co-centered anionic states. This work expands the family of transition-metal-based electrides and highlights dimensionality engineering as a powerful strategy for tuning electronic and magnetic properties.