Antiferromagnetic-coupling-induced magnetoresistance enhancement in Fex(TiO2)1-x films

Fe-incorporated amorphous TiO2 films with different Fe volume fractions of 0.46 <= x <= 0.76 were deposited by cosputtering iron and Ti targets in an Ar+O-2 mixture. X-ray diffraction and x-ray photoelectron spectroscopy analyses give a structure of nanosized Fe particles embedded in amorphous TiO2 matrix for the Fe-x(TiO2)(1-x) films. Magnetic measurements show antiferromagnetic coupling between nanoscaled Fe granules when x < 0.60. The magnetoresistance of Fe-0.46(TiO2)(0.54) is about -7.6% at room temperature, which increases dramatically with decreasing temperature below similar to 100 K and reaches -29.3 % at 3 K. This significant enhancement of magnetoresistance can be qualitatively explained by antiferromagnetic coupling between Fe granules. (c) 2006 American Institute of Physics.