The Flexible Fecosib Amorphous Magnetoelastic Film Stress Impedance Effect

Amorphous FeCoSiB thin films possesses large magnetoelastic and stress-impedance effect(SI),and can be used in stress sensors.Moreover,the stress sensors prepared by FeCoSiB thin films on flexible substrate can be applied in the stress detection and control of non-plane surfaces.In this thesis,the micromagnetic model of FeCoSiB/Metal/FeCoSiB multi-layers were deduced.The efficiency permeability and the stress-impedance effect of FeCoSiB/Metal/FeCoSiB multi-layers were calculated by the solution of Landau-Lifshitz-Gilbert equation and the Maxwell equations.The influences of the thickness of the ferromagnetic and the conductive layers,the conductance of the metal layer,the saturation magnetization,and the testing frequency on the stress-impedance effect of the FeCoSiB/Metal/FeCoSiB multi-layers were discussed.Experimentally,the FeCoSiB thin film and FeCoSiB/Cu/FeCoSiB multi-layers were prepared on a flexible substrate by DC magnetron sputtering,and the influences of the sputtering parameters on the stress-impedance effect of the samples were researched systematically.The theoretical calculation results show that the stress-impedance effect increases with the increase of the thickness of the magnetic layer,the saturation magnetization of the magnetic layer and the conductance of the metal layer.Therefore,the stress impedance effect can be improved obviously by increasing the thickness of the magnetic layer,the saturation magnetization of the magnetic layer and the conductance of the metal layer.Moreover,the stress-impedance effect increases gradually with the increase of the testing frequency at lower frequency,then decreases gradually with the increasing testing frequency at higher frequency.The experimental results show that the maximum stress impedance effect of the FeCoSiB thin films prepared at argon pressure of 1.5 Pa can be obtained.The maximum stress impedance effect of FeCoSiB thin films is 7.6%at 25 MHz.Induction magnetic anisotropy in FeCoSiB thin films is improved by applied bias magnetic field during the preparing of the samples,which results in the increasing of stress impedance effect obviously.For the FeCoSiB samples prepared at 65 Oe,the stress impedance effect is 4.0%at 25MHz.However,for the FeCoSiB samples prepared at 1000 Oe,the stress impedance effect is 7.6%at 25 MHz.For FeCoSiB/Cu/FeCoSiB multi-layers,the stress impedance effect is 1.75%for bias magnetic filed of 65Oe,and 6.61%for bias magnetic filed of 1000Oe.When the thickness of the ferromagnetic layer is 2μm,the stress impedance effect of the FeCoSiB/Cu(1μm )/FeCoSiB and FeCoSiB/Cu (0.5μm)/FeCoSiB multi-layers is 6.61%and 1.62%at 25MHz,respectively.When the thickness of the Cu layer is 1μn,the stress impedance effect of the FeCoSiB(1μm)/Cu /FeCoSiB(1μm) and FeCoSiB(2μm)/Cu/FeCoSiB(2μm) multi-layers is 5.03%and 6.61%at 25MHz,respectively.