Stress-dependence of magneto-polarization effect in magnetic amorphous microwires
Miniature sensors with remote wireless operation are required in many technological areas including structural health monitoring, smart composites, embedded biosensors, etc. Microwave technologies have a high potential for remote sensing applications. This paper concerns modelling a tunable microwave electric polarization of magnetic amorphous microwires to investigate potential applications in sensors.
The sensor operation will be based on large change in the wire surface impedance caused by the change in a magnetic structure by external stress(known as stress-magnetoimpedance effect). The absence of the crystalline structure is very useful since it is possible to induce a required magnetic anisotropy through magnetoelastic interaction. For microwave sensing applications, the magnetic structure in the outer shell of a circumferential or helical type is preferable, which can be established in Co-rich alloys with negative magnetostriction. For such wires, the remagnetisation behaviour in an axial magnetic field less than the effective anisotropy field is almost linear, without hysteresis and with very high susceptibility. The external stress and temperature can substantially modify the magnetic anisotropy and the magnetization processes.
Tunable soft magnetic properties of amorphous microwires result in unique high frequency behavior, namely, giant magnetoimpedance. At MHz frequencies, MI is utilized in various magnetic and stress sensors. At GHz frequency, the MI effect can be used to control the scattering of electromagnetic waves from microwires with application to tunable electromagnetic composites and embedded sensors. Here we demonstrate that scattering from a ferromagnetic microwire showing large MI effect at microwaves can be modulated with low frequency magnetic field and the amplitude of this modulation near the antenna resonance can sensitively change in the presence of the external stress or temperature. The modelling is based on solving the scattering problem from a cylindrical wire with the impedance boundary conditions.
Научный руководитель - профессор к.ф-м.н. Панина Лариса Владимировна.