Caracterização de multicamadas de NiFe/FeMn para medidas de magnetoimpedância assimétrica abaixo de 2 GHz

Abstract

In this work the giant magnetoimpedance effect (GMI) was investigated in exchange biased Ni81Fe19/Fe50Mn50 bilayers. The study samples were deposited on glass substrate by magnetron sputtering. The exchange bias (EB) was induced during the deposition by the aplication of a 2 kOe static field. The studied parameters were the thickness of the ferromagnetic material (NiFe) that was varied between 150 and 250 nm and the number of bilayers n = 1, 2 and 3. The structural characterization was performed by high angle x-ray difraction (XRD) technique in a configuration − 2 and using Cu- K radiation. The static magnetic characterization was performed with a alternating gradient field magnetometer (AGFM). The resistive and reactive components of the impedance were measured as function of the frequency (100 MHz-1,8 GHz) and the static field (H = ±200 Oe). The results shown that the effect increase with the number of bilayers reaching about 300% for n = 3. The Z vs. H curves show good linearity for |H| 1 Oe, the sensitivity also grows with the thickness of the NiFe and the number of bilayers reaching 9% /Oe for n = 3.