Giant magnetoimpedance in FM/SiO2/Cu/SiO2/FM films at GHz frequencies

We study the magnetic properties at high frequency of new structures of the tri-layer samples. The magnetoimpedance effect was analyzed in FM/i/Cu/i/FM sandwiched layers, where the ferromagnetic layer (FM) is, in fact, a multilayered film [F (10nm) + Cu (1 nm)] x 50 and F is the amorphous ferromagnetic alloy Fe(73.5)Cu(1)Nb(3)Si(13.5)B(9) and i is an isolating layer produced by magnetron sputtering. The effect of, both, the probe current frequency (in the range 10 MHz-1.8 GHz) and the dimensions of the magnetic and nonmagnetic layers of the MI response were investigated. A comparison between samples with and without the isolating layer is discussed. MI ratios of 220% were obtained for samples at 180MHz with a ferromagnetic and Cu width layers of 2 and 1 mm, respectively. (C) 2008 Elsevier B. V. All rights reserved.