Magnetotransport properties of inverse-spinel Cr x Fe 3 − x O 4 thin films

• Published in: Journal of applied physics 2008-10, Vol.104 (8), p.083912-083912-5
• Main Authors: Kim, Kwang Joo, Lee, Hee Jung, Lee, Jung Han, Lee, Seungho, Kim, Chul Sung
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3000625

Magnetotransport properties of Cr x Fe 3 − x O 4 ( x ≤ 0.95 ) thin films prepared using a sol-gel method were measured and analyzed in comparison with their magnetic properties. The samples were polycrystalline and exhibited a slight decrease in lattice constant as the Cr composition ( x ) increases. The observed decreasing trend in the saturation magnetization ( M s ) of Cr x Fe 3 − x O 4 with increasing x can be explained in terms of the decrease in net spin magnetic moment due to the substitution of Cr 3 + ( 3   μ B ) for octahedral Fe 3 + ( 5   μ B ) . The magnetoresistance (MR) of the Cr x Fe 3 − x O 4 films was found to increase in a linear manner with increasing external field ( H ≤ 5   kOe ) while the observed magnetization of the samples started to saturate near H = 2   kOe . For a given H , MR decreases with increasing x . The observed increase in MR with increasing H in Cr x Fe 3 − x O 4 is mainly attributable to the reduction in tunneling resistance of spin-polarized carriers through grain boundaries (GBs). Transition layers of magnetization formed around magnetic defects in the GBs are likely to be connected to the spin-dependent tunneling. The decrease in MR with increasing x is attributable to the disorder-induced scattering.