Asymmetric magnetoimpedance effect in ferromagnetic multilayered biphase films

Abstract

effect in ferromagnetic multilayered biphase films, Journal of Magnetism and Magnetic Materials, http://dx.We investigate the magnetoimpedance effect in ferromagnetic multilayered biphase films. We verify that the films present asymmetric magnetoimpedance behavior and, by playing with the number of the repetitions of the base structure of the multilayer and the probe current frequency, we explore the possibility of tailoring the linear region around zero magnetic field in order to achieve higher sensitivity values. The highest sensitivity is observed for the thicker film, reaching ∼ 15 mΩ/Oe at ∼ 0.52 GHz. Thus, the results open the possibilities for application of ferromagnetic multilayered biphase films with asymmetric magnetoimpedance effect in sensors devices.

Asymmetric Magnetoimpedance in Bimagnetic Multilayered Film Structures

“…Although the results of modeling describe main features of the AMI effect in bimagnetic multilayered films [12], some experimental data cannot be explained in the framework of the model proposed. It was observed that at frequencies above 1.5 GHz the shape of the impedance field dependence changes.…”

“…To investigate the effect of the magnetostatic coupling and number of layers on the MI ratio, we use geometrical parameters of the bimagnetic multilayers studied experimentally [12]. The MI ratio DZ/Z 0 is defined as follows:…”

“…We assume that the magnetic layers have the uniaxial in-plane anisotropy. During the deposition of the multilayer, a constant magnetic field was applied along the short side of the film [12]. Therefore, the direction of the anisotropy axes in the magnetic layers is close to the transverse one.…”

“…This is due to the first soft magnetic layer interacts only with one hard magnetic layer, whereas the other soft magnetic layers are sandwiched between two hard magnetic layers [12]. To take into account this fact, we assume that the bias field in the first soft magnetic layer is two times lower than H b .…”

“…This fact is related to the small thickness of the film structure, where the skin depth is much larger than the film thickness. To enhance the sensitivity of the AMI, the multilayers consisting of a repetition of the base bimagnetic three-layered film structure have been proposed [12]. It was found that these multilayers exhibit bimagnetic behavior, and the AMI sensitivity increases, which is promising for sensor design.…”