科研之友
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摘要
We report an enhanced room temperature magnetoimpedance (-12.3 %) effect in ball milled Fe3O4 particles. The crystalline structure, magnetic and transport properties indicate that an insulating alpha-Fe2O3 layer exists on the surface of the Fe3O4 particles during the ball milling process. Based on Simmons model, a series of non-linear current-voltage (I-V) curves display the change of barrier thickness and barrier height with respect to ball milling time. More importantly, Nyquist plots show that the grain boundary resistivity is sensitive to the applied magnetic field and dominates the magnetotransport properties. We assume that an appropriate barrier thickness plays a crucial role in the enhancement of the magnetoimpedance effect based on spin-dependent tunnelling.
