| Electrical transport and magnetoresistance characteristics were investigated for sintered Fe₃O₄-xFe (x = 0, 10, 20 wt.%) specimens. For composition dependence of Fe₃O₄-xFe specimens sintered at 500℃, the largest MR of 3.3% at 10 kOe was obtained in Fe₃O₄-10Fe specimen. It was found that this enhanced MR appears together with the appropriate excess resistance, which regarded as tunneling barrier, in the interparticle of Fe₃O₄. It indicates that the enhanced MR ratio arises from the spin dependent tunneling effect and can be explained with increased interparticle contacts. On the other hand, for the sintering temperature dependence of Fe₃O₄-xFe samples, the MR ratios decrease with the increased sintering temperature. The decreased MR ratios for Fe₃O₄-xFe may be associated with the decreased resistance due to the growth of Fe₃O₄ particles in Fe₃O₄ specimen and inadequately increased tunneling barrier of Fe_(l-x)O particles in Fe₃O₄-10, 20Fe specimens. |
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