Complex impedance spectroscopy of Mn-doped zinc oxide nanorod films

The frequency-dependent properties of Mn-doped (3–5 at.%) aligned zinc oxide (Mn–ZnO) nanorods, synthesized by hybrid wet chemical route onto glass substrates, were investigated by bias-dependent impedance spectroscopy. No peak of Mn cluster/secondary phases was detected in the X-ray diffraction traces of the samples. XPS studies show the presence of oxygen vacancies in Mn–ZnO nanorods and Mn in Mn2+ and Mn4+ charge states. Although X-ray diffraction/X-ray photoelectron spectroscopy does not give any indication of the presence of metal clusters in the samples, bias-dependent impedance spectroscopy demonstrates significant sensitivity to the formation of Mn clusters in Mn–ZnO nanorods.

► Detailed investigations on Mn-doped ZnO nanorods are carried out.
► Magnetic clusters are detected using bias-dependent impedance spectroscopy (IS).
► Relaxation time (τ) is estimated from equivalent circuit analysis.
► Metal clusters are shown to contribute to the final impedance of the sample.
► Impedance spectroscopy is used as a tool for understanding the origin of magnetism.