Emerging two-dimensional magnetism in nonmagnetic electrides <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mi>Hf</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mi>X</mml:mi></mml:mrow></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mi>X</mml:mi><mml:mo>=</mml:mo><mml:mtext>S</mml:mtext><mml:mo>,</mml:mo><mml:mo> </mml:mo><mml:mi>Se</mml:mi><mml:mo>,</mml:mo><mml:mo> </mml:mo><mml:mi>Te</mml…

Recent experimental discoveries of two-dimensional (2D) magnets have triggered intense research activities to search for atomically thin magnetic systems. Using first-principles calculations, we predict the emergence 2D magnetism in monolayers (MLs), few layers, and surfaces nonmagnetic layered electrides ${\mathrm{Hf}}_{2}X$ $(X=\text{S}, \mathrm{Se}, \mathrm{Te})$ consisting three-atom-thick $\mathrm{Hf}\text{\ensuremath{-}}X\text{\ensuremath{-}}\mathrm{Hf}$ stacks. It is revealed that each bulk hosts a quantum state Dirac nodal lines with high density states arising from $\mathrm{Hf}\text{\ensuremath{-}}5d$ cationic interlayer anionic electrons around $\ensuremath{-}0.9 \mathrm{eV}$ below Fermi level ${E}_{F}$. However, MLs, ${\mathrm{Hf}}_{2}X$, such hybridized are shifted toward ${E}_{F}$ generate van Hove singularities, leading Stoner instability. The resulting surface ferromagnetism gives rise strongly spin-polarized topological at ${\mathrm{Hf}}_{2}X(001)$, demonstrating electrons, magnetism, band topology entangled other. Our findings will open different perspectives discovery via exploiting effects electrides.