Magnetic properties of Mn doped ZnO: the role of synthesis route

Structural, morphological, optical, magnetic properties and chemical state of the constituent elements of 2 at% Mn doped ZnO samples synthesized by solid state reaction and sol-gel techniques were analyzed. The role of chemical or valency state in tuning the magnetic properties has been investigated. X-ray diffractometer, scanning electron microscope, UV-visible and X-ray photoelectron spectroscopes and superconducting quantum interference device vibrating sample magnetometer (SQUID VSM) were employed for investigation. Mn incorporation in ZnO lattice has been shown by single phase wurtzite structured samples. The presence of defects particularly zinc vacancy (V-Zn) has been evidenced from band tailing. Solid state reaction technique derived sample exhibit strong intrinsic ferromagnetism but sol-gel sample didn't show strong ferromagnetic (FM) ordering. Antiferromagnetic (AFM) interaction is present in both samples. The chemical state of Mn is +2 for solid state reaction technique derived sample whereas for sol-gel technique derived sample it is a mixed chemical state (exists in both +2 and +3 states). Finally, the peculiar magnetic behavior has been interpreted from the interaction between V-Zn and d-electrons of Mn2+ and Mn3+ states.