Room temperature ferromagnetism in Mn and Fe-doped indium-tin oxide films

Following the reports of high temperature ferromagnetism in n-type Mn-doped Indium tin oxide (ITO) thin films, we have undertaken a systematic investigation of the magnetic and transport properties of ITO thin films doped with all the 3d transition metal ions. ITO films were grown on c-cut sapphire substrate by pulsed laser deposition. The X-ray diffraction patterns reveal that they are oriented mainly in (111) direction of cubic bixbyite structure. Undoped ITO films are diamagnetic. Room temperature ferromagnetism is observed in Fe and Mn-doped thin films of varying concentrations, when deposition temperatures are greater than 600\r{ }C. The largest magnetic moments were found in 2.5{\%} Mn-doped and 7.5{\%} Fe-doped ITO films. The Mn-doped films are anhysteretic, while the Fe-doped films exhibit a hysteresis with a coercivity of 30 mT and a moment which increases with concentration. However, in the Mn-doped samples, we see a higher moment for the lower concentrations. None of the other doped ITO films were found to be magnetic, ruling out the possibility of cluster based magnetism. Conversion electron M\"{o}ssbauer spectra of the ferromagnetic iron-doped films show the presence of magnetite in quantities sufficient to explain the magnetization. No such secondary phase is found for Mn.