Giant magnetoimpedance effect in Co2FeAl single layered and Co2FeAl/Ag multilayered films in amorphous substrates

We investigate the structural, quasi-static and dynamic magnetic properties of a Co2FeAl single layered film and a Co2FeAl/Ag multilayer, both grown onto amorphous substrate. We verify that both films have A2 structure and anisotropic magnetic behavior, as well as present the well-known magnetoimpedance behavior of anisotropic systems. The magnetization dynamics is discussed in terms of the mechanisms that govern the magnetoimpedance effect in a wide range of frequencies, as well as of the orientation between the external magnetic field and electrical current with respect to the magnetic anisotropy. The single layer has the largest magnetoimpedance variations values of similar to 50% for 3.0 GHz, while the multilayer present considerable higher values, reaching to similar to 200% at the same frequency. The association of kind of sample structure, anisotropic magnetic behavior and low damping parameter a of the CFA alloy opens possibilities to reach higher magnetoimpedance performances. The results place the CFA full-Heusler alloy as a promising candidate for applications in magnetoimpedance-based sensors and radio frequency range devices. (C) 2015 Elsevier B.V. All rights reserved.