Faraday effect in ZnO:Mn thin films

Undoped and Mn-doped ZnO transparent thin films were grown by RF magnetron co-sputtering. The films are nanocrystalline, with wurtzite-structure grains of a typical size of 20 nm, with a preferential orientation of the c-axis perpendicular to the surface. Although, according to the Raman spectroscopy data, Mn mostly substitutes Zn in the lattice sites, factor that is considered favorable for ferromagnetism in this material, the ZnO:Mn films are paramagnetic at room temperature as it follows from our Faraday effect (FE) measurements. The FE spectra show a significant influence of the Mn ions for photon energies sufficiently below the ZnO:Mn band gap but not in its vicinity.