Phys. Status Solidi RRL 5, 12, 438 (2011)

M. Lorenz, M. Brandt, K. Mexner, K. Brachwitz, M. Ziese, P. Esquinazi, H. Hochmuth, and M. Grundmann

Abstract

The electrical conductivity of zinc ferrite (ZFO) thin films can be tuned over 7 orders of magnitude. The conductivity is thermally induced with two activation energies around 40–55 meV and 70–130 meV. Doping of the ZFO films with 1 at% Si or Ge further increases the conductivity. The magnetic hysteresis shows coercive fields of about 0.01 T and high saturation magnetization up to 300 emu/cm³ at 300 K. The electronic Hall mobility and carrier concentration at high magnetic fields are about 0.07 cm²/V s and 1.2 × 1020 cm^-3 at room temperature, respectively, which indicates a hopping dominated conductivity. The out-of-plane orientation of the ZFO films fabricated by pulsed laser deposition is (001) on SrTiO₃(001) and (111) on SrTiO₃(111).

The resistivity of ZnFe₂O₄ thin films on SrTiO₃ is tunable over 7 orders of magnitude by the PLD growth parameters and doping with group IV elements.