Pressure-Induced Isostructural Antiferromagnetic-Ferromagnetic Transition in an Organic Electride

Electrides are ionic solids in which cavity-trapped electrons act as anions. These materials have a number of unusual magnetic and electronic properties that originate from the free electrons localized in the crystal voids. Antiferromagnetic (AFM) behavior has previously been observed in organic electride crystals, while it has recently been demonstrated that two-dimensional electrides show strongly anisotropic electrical conductivity and weak itinerant ferromagnetism. In this work, we study the behavior of the simplest organic electride (Cs+(15-crown-5)(2)e(-)) under pressure using dispersion-corrected density functional theory. We predict that this electride undergoes an AFM to FM isostructural transition in the 0.5 to 1.0 GPa range. The electride character of the material is preserved through the transition, which originates exclusively from the spin coupling of the electrons trapped in the crystal voids. The pressure required for the magnetic transition is easily accessible using modern experimental techniques, which opens the door to potential magnetoelectric applications for electride materials.