Identification of long-range order of electrons in novel electride Ca5P3(e- )

Electrides are novel class of materials characterized by the stoichiometric presence of trapped electrons within a cationic framework, where such electrons behave similarly to anions. Much like the localized d- or f- electrons in conventional systems, electrides exhibit a variety of exotic properties owing where the degrees of freedom of the electride electron coupled with the underlying geometry and size of the cationic cavities come into play. However, detection and characterisation of electride electrons is challenging which has hindered their targeted design. We discovered a new candidate electride material Ca5P3(e-) comprising non-magnetic ions which undergoes long-range magnetic order around TN ~ 30K. As both Ca2+ and P3- ions are non-magnetic it is highly likely the observed magnetic behavior arises solely from the electride electrons. Ca5P3(e-) may be therefore the first known inorganic electride exhibiting such a magnetic transition originating solely from electride electrons. We aim to determine the magnetic structure of Ca5P3(e-) with neutron diffraction using WISH neutron diffractometer. Magnetic Bragg reflections would provide direct evidence of the presence of electride electrons, which would uncover crucial insights into the magnetic properties driven by electride electrons, thereby advancing our understanding of these exotic materials.