Applied Surface Science, Vol.255, No.10, 5245-5247, 2009
Thin films of semiconducting lithium ferrite produced by pulsed laser deposition
Thin films of lithium ferrite (Li0.5Fe2.5O4) have been deposited on (0 0 1) Al2O3 by pulsed laser deposition, with substrate deposition temperatures ranging between 500 and 800 degrees C, and oxygen pressures between 1 x 10 (-1) and 4 x 10 (-7) mbar. X-ray diffraction shows that films grow with a (1 1 1) orientation. Conversion electron Mossbauer spectra for the high-pressure films show a single sextet with a hyperfine field of 49 T, while the low-pressure films show two sextets with hyperfine fields of 47 and 49 T. The spectra also reveal paramagnetic ferric iron in both types of films. Magnetization measurements of the films show a saturation magnetization of between 1.7 and 3.1 mu(B) per formula unit and a coercivity of between 10 and 44 mT. The films prepared under the lower oxygen pressures are semiconducting with resistivities of 2 x 10 (-2) to 8 x 10 (-2) Omega cm. They exhibit an anomalous Hall effect with p-type conduction at 175 K. (C) 2008 Elsevier B. V. All rights reserved.