Large room-temperature spin-dependent tunneling magnetoresistance in polycrystalline Fe[sub 3]O[sub 4] films

Hui Liu; Jiang, E.Y.; Bai, H.L.; Zheng, R.K.; Wei, H.L.; Zhang, X.X.
October 2003
Applied Physics Letters;10/27/2003, Vol. 83 Issue 17, p3531
Academic Journal
Polycrystalline Fe[sub 3]O[sub 4] films have been prepared by reactive sputtering at room temperature. Transmission electron microscopy images show that the films consist of quite uniform Fe[sub 3]O[sub 4] grains well separated by grain boundaries. It was found that the tunneling of spin-polarized electrons across the antiferromagnetic coupled grain boundaries dominates the transport properties of the films. Magnetoresistance (MR) {=[ρ(H)-ρ(0)]/ρ(0)} shows linear and quadratic magnetic-field dependence in the low-field range when the field is applied parallel and perpendicular to film plane, which is similar to the behaviors observed in the epitaxial Fe[sub 3]O[sub 4] films consisting of a large fraction of antiferromagnetic antiphase domain boundaries. At 300 K, the size of the MR reaches -7.4% under a 50-kOe magnetic field, which is a very large MR for polycrystalline Fe[sub 3]O[sub 4] films. © 2003 American Institute of Physics.


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