Grain boundary defects induced room temperature ferromagnetism in V doped ZnO thin films

Vanadium (V) doped ZnO thin films (Zn_1‐xV_x O, where x = 0, 0.05, 0.10) have been grown on sapphire substrates by RF magnetron sputtering to realize room temperature ferromagnetism (RTFM). The grown films have been subjected to X‐ray diffraction (XRD), resonant Raman scattering, photoluminescence (PL) and vibrating sample magnetometer (VSM) measurements to investigate their structural, optical and magnetic properties, respectively. The full width at half maximum of XRD and Raman scattering peaks increases with V ion concentration indicates that the V ions have been substituted on Zn²⁺ ions in the ZnO matrix. The increase in oxygen vacancies with V concentration is evidenced by PL measurements. Rutherford backscattering spectrometry analysis confirms the presence of the V ions in the films. The room temperature VSM measurements reveal the signature of ferromagnetism in V doped ZnO thin films. It has been observed that the grain boundary defects, i.e., oxygen vacancies play a crucial role in inducing RTFM in V doped ZnO films. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)