Structure and magnetic properties of Cr/Fe-doped SnO2 thin films

Cr- and Fe-doped SnO2 films were deposited on Al2O3 substrates by pulsed-laser deposition. X-ray-diffraction patterns show that the films have rutile structure and grow epitaxially along the (101) plane. The diffraction peaks of Cr-doped samples exhibit a systematic shift toward higher angles with increasing Cr concentration. This indicates that Cr dissolves in SnO2. On the other hand, there is no obvious shift of the diffraction peaks of the Fe-doped samples. The magnetization curves indicate that the Cr-doped SnO2 films are paramagnetic at 300 and 5 K. The Fe-doped SnO2 samples exhibit ferromagnetic behavior at 300 and 5 K. Zero-field-cooled and field-cooled curves indicate superparamagnetic behavior above the blocking temperature of 100 K, suggesting that it is possible that there are ferromagnetic particles in the Fe-doped films. The anisotropic magnetoresistance was not observed in any of the samples. (C) 2006 American Institute of Physics.