Unveiling the correlation between structural and magnetic ordering in nano Co 1- x Ni x TeO 4 .

Nanomaterials with unique structures and exotic magnetic phenomena are always intriguing; however, the direct correlation of structural and magnetic ordering up to a few nanometers remains critical. We report structural and magnetic properties of sol-gel grown Co 1- x Ni x TeO 4 ( x = 0, 0.5 and 1) nanoparticles. An increase in the calcination temperature leads to the enhancement of the particle size and structural ordering. This is accompanied by changes in the magnetic interactions as well. Calcination at lower temperatures retains the short-range non-crystalline structure and superparamagnetic behavior, while calcination at higher temperatures results in long-range ordering in both the crystal and magnetic structures. Superparamagnetic to antiferromagnetic ordering observed from temperature- and field-dependent magnetization is attributed to the changes in structural ordering. This study presents a new family of nanomaterials displaying stable magnetic order up to ∼6 nm, where the magnetic properties can be uniquely controlled by changing the structural ordering.