Magnetic ordering in the spinel compound Li[Mn2-xLix]O4(x=0,0.04)

Abstract

The two B-site ions Mn3+ and Mn4+ in the stoichiometric spinel structure LiMn2O4 form a complex, columnar ordered pattern below the charge-ordering transition at room temperature. On further cooling to below 66 K, the system develops long-range antiferromagnetic order. In contrast, whereas lithium-substituted Li[Mn2-xLix]O4 also undergoes a charge-ordering transition around room temperature, it only displays frozen in short-range magnetic order below ~25-30 K. We investigate to what extent the columnar charge-order pattern observed in LiMn2O4 can account for the measured magnetic ordering patterns in both the pure and Li-substituted (x = 0.04) compounds. We conclude that eightfold rings of Mn4+ ions form the main magnetic unit in both compounds (x = 0,0.04), and that clusters formed out of these rings act as superspins in the doped compound.