薄膜厚度对多层膜巨磁阻抗效应的影响研究

Thickness effect on giant magnetoimpedance in multilayered films

采用磁控溅射方法在玻璃基片上制备了FesiB/cu/FesiB多层膜,在100kHz～40MHz范围内研究了FesiB薄膜厚度对FesiB/Cu/FesiB多层膜巨磁阻抗效应的影响。当磁场施加在薄膜的纵向时,巨磁阻抗效应随磁场的增加而增加,在某一磁场下达到最大值,然后随磁场的增加而下降到负的巨磁阻抗效应。当FesiB薄膜的厚度为1.8μm时,在频率3.2MHz、磁场2.4kA/m时,多层膜巨磁阻抗效应达最大值13.5％;在磁场为9.6kA/m时,巨磁阻抗效应为-9.2％。然而,当FesiB薄膜的厚度为1μm时,多层膜的巨磁阻抗效应在频率40MHz、磁场1.6kA/m时达最大值5.8％。另外,当磁场施加在薄膜的横向时,薄膜表现出负的巨磁阻抗效应。对于膜厚为1.8μm的FeSiB薄膜,在频率5.2MHz、磁场9.6kA/m时,巨磁阻抗效应为-12％。可见巨磁阻抗效应的最大值及负的巨磁阻抗效应与多层膜中磁各向异性轴的取向及FeSiB薄膜的厚度有关。

Giant magnetoimpedance (GMI) effect was investigated in the frequency range of 100kHz～40MHz in multilayered FeSiB/Cu/FeSiB with different thickness of FeSiB films. With magnetic field H_a applied along the longitudinal direction of the sample, the GMI ratio increases with H_a, reaching a posttive maximum value at a certain field and then decreases to the negative GMI ratio with further increase of H_a. At a frequency of 3.2MHz, the positive maximum GMI ratio is 13.5% for H_a = 2.4kA/m, and a larger negative GMI ratio, - 9.2% is obtained for H_a = 9.6kA/m in multilayered FeSiB/Cu/FeSiB films which FeSiB film is 1.8μm thick. While, for multilayered FeSiB/Cu/FeSiB films which FeSiB film is 1.0μm thick, the maximum GMI ratio of 5.8% is obtain at 1.6kA/m for a frequency of 40MHz. In addition, the multilayered films displayed large negative GMI ratio with magnetic field applied along the transverse direction of the samples, and a negative GMI ratio, -12% is obtained at 5.2MHz for H_a= 9.6kA/m in multilayered FeSiB/Cu/FeSiB films with FeSiB film thickness of 1.8μm. The large negative GMI ratio and the positive maximum CMI ratio are correlated to the easy axis orientation and the thickness of FeSiB film in the multilayered FeSiB/Cu/FeSiB films.