NMR studies on antiferromagnetism in alkali-electro-sodalite

Abstract We report 27 Al-NMR and DC-magnetic susceptibility measurements on recently discovered alkali-electro-sodalite (AES, A=Sodium, Potassium). AES is known to be a Mott insulator consisting of a body-centered-cubic lattice of F -centers. 27 Al-NMR measurements demonstrate that SES (S=Sodium) and PES (P=Potassium) undergo an antiferromagnetic transition around T N ∼48 and 70 K, respectively. Magnetic properties, especially on the temperature dependence of the susceptibility, seem to be quite sensitive to the size of the F -centers.