| u and (Ni80Fe20/SiO2)n/Cu composite wires were prepared by RF magnetron sputtering. By measuring GMI curve and hysteresis loops, we studied the influence of outer-layer Ni80Fe20thickness and cycle n on GMI, AGMI effect and magnetic structure. The main results are as follows:1. In the samples of Ni80Fe20/Fe50Mn50/Ni80Fe20/Cu composite wires, AGMI effect of different outer-layer Ni80Fe20thickness were studied, we found:(1) When the thickness of inner-layer Ni80Fe20、Fe50Mn50and Cu base remain unchanged, with the increase of outer-layer Ni8oFe2o thickness, magnetic structure of samples will change from longitudinal to circumferential direction, the AGMI effect will be gradually weaker. With the increase of the amplitude and frequency of the driving current, the AGMI effect firstly becomes stronger and then weaker.(2) The maximum MI ratio will decline with the decrease of the sample’s length, but this will not affect the AGMI effect. Besides, AGMI effect strongly depends on the measuring direction of DC magnetic field. When the field is along circumferential direction of the sample, there will be about15Oe offset in GMI curve.2. In the samples of (Ni80Fe20/SiO2)n/Cu composite wires, magnetic properties and GMI effect were studied, the results are shown in the following two aspects:(1) The total thickness of Ni80Fe20and SiO2were controlled at8.4μm and6.5μm respectively. With the increase of cycle n, both circumferential anisotropy field and coercivity increase gradually; the samples’magnetic structure will change from longitudinal to circumferential direction. MI ratio firstly increases then decreases which results from the competition between magnetic structure, coercivity and interface effect.(2) The initial and characteristic frequency will firstly decrease and then tend to moderate with the increase of cycle n. When n=2, the sample has the best magnetic properties, the maximum MI ratio reaches527.9%, anisotropy field is only1.22Oe, The field sensitivity is57%/Oe. |
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