Magnetoimpedance In Amorphous Ribbons Research Articles

Magnetoimpedance and Field Sensitivity of CoFeSiB Amorphous Ribbons under Applied Tensile Stress

Magnetoimpedance (MI) and field sensitivity of CoFeSiB amorphous ribbons were investigated at frequencies ranging from 0.2 to 12 MHz after tensile stress applied. Experimental results indicate that the MI of amorphous ribbons can be significantly improved by applying a suitable longitudinal tensile stress. Applying tensile stress induces a rearrangement of domain walls which influences the circumferential anisotropy and magnetic permeability result in improving the MI response. The maximum MI response of 145 % and maximum field sensitivity of 6.32 %/Oe at frequency of 4 MHz were obtained, when tension was equivalent to 120 MPa. So the tensile stress as new method can be effective, cheap, and fast in sensor applications, and result of this investigation can be applied for the design of the stress sensors based on the giant magnetoimpedance effect.

Nonlinear Magnetoimpedance in Field- and Stress-Annealed Amorphous Ribbons

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The diagonal and off-diagonal nonlinear magnetoimpedance in amorphous ribbons with well defined magnetic anisotropy is investigated. Field- and stress-annealing are used to produce easy-ribbon-axis and hard-ribbon-axis anisotropy, respectively. The dependence of the first three harmonic components of impedance on applied magnetic field and dc bias current is discussed. The symmetry properties of diagonal and off-diagonal impedance components as functions of applied magnetic field and dc bias current are substantially different. While all the components of diagonal impedance are mainly symmetric functions of field, the off-diagonal impedance is mainly antisymmetric. It is found that the odd harmonics of diagonal impedance can be related to the second harmonic of the off-diagonal impedance and vice versa. A theoretical explanation of the observed behavior, based on the symmetry properties of nonlinear Landau–Lifshitz–Gilbert equation, is proposed. </para>

Domains and giant magneto-impedance in amorphous ribbons by magneto-optical Kerr effect

By longitudinal magneto-optical Kerr effect microscopy we analyzed the development of the domain structure in Co70.4Fe4.6Si15B10 amorphous ribbons for which giant magneto-impedance had been observed. Using transverse and longitudinal magneto-optical Kerr effect magnetometry we measured the magnetization direction around the hysteresis loop. These results allowed us to model the domain structure of the sample during the giant magneto-impedance measurements.