  Electrides are special ionic solids with excess cavity-trapped electrons
serving as anions. Despite the extensive studies on electrides, the interplay
between electrides and magnetism is not well understood due to the lack of
stable magnetic electrides, particularly the lack of inorganic magnetic
electrides. Here, based on the mechanism of Stoner-type magnetic instability,
we propose that in certain electrides the low-dimensionality can facilitate the
formation of magnetic ground state because of the enhanced density of states
near the Fermi level. To be specific, A5B3 (A = Ca, Sr, Ba; B = As, Sb, Bi)
(1D), Sr11Mg2Si10 (0D), Ba7Al10 (0D) and Ba4Al5 (0D) have been identified as
stable magnetic electrides with spin-polarization energies of tens to hundreds
of meV per formula unit. Especially for Ba5As3, the spin-polarization energy
can reach up to 220 meV. Furthermore, we demonstrate that the magnetic moment
and spin density mainly derive from the interstitial anionic electrons near the
Fermi level. Our work paves a way to the searching of stable magnetic
electrides and further exploration of the magnetic properties and related
applications in electrides.
