Spin selective non-van der Waal electride nature in manganese under ambient pressure
Electrides are an unusual class of ionic materials in which electrons localized in non-nuclear, interstitial regions act as anions within the crystal lattice. Here, we employ first-principles quantum mechanical calculations to investigate the structural, electronic, magnetic, and electride characteristics of elemental manganese (Mn) at an ambient pressure (0 GPa), focusing on its three crystalline phases: cubic ($\alpha$)-Mn ($I\bar{4}3m,no.217$), cubic ($\beta$)-Mn ($P4_132, no.213$), and hexagonal ($hex$)-Mn ($P6_3/mmc, no.194$). Our calculations reveal pronounced interstitial-electron character in all three phases, accompanied by spin-selective electron localization function (ELF), establishing elemental Mn as a non-van der Waals electride system. Bader charge analysis indicates substantial electron redistribution from the Mn host framework toward the interstitial anionic-electron (IAE) regions, with an effective charge transfer of approximately $-1.645e$, $-1.477e$, and $-1.083e$ per interstitial basin in $\alpha$-Mn, $\beta$-Mn, and $hex$-Mn, respectively. The electride character is further supported by the electronic density of states, where the IAE-associated states exhibit finite contributions near the Fermi level ($E_F$) and coexist with Mn-derived states, demonstrating their direct participation in the low-energy electronic structure. The combined electron localization function (ELF), effective charge transfer, and electron population due to IAE at $E_F$ therefore provide consistent evidence for interstitial anionic electrons in elemental Mn. To the best of our knowledge, this work provides the first systematic identification of spin-selective electride character in elemental Mn at ambient pressure, highlighting the possibility of exploiting its interstitial-electron states for unconventional electronic and magnetic functionalities.