High-frequency harmonics in amorphous magnetic microwires for wireless sensor application
Ferromagnetic microwires with amorphous or nanocrystalline structure have a number of specific magnetic properties: magnetic bi-stability, very large magnetoimpedance and stress-impedance. All these effects can find applications in various sensors. From the application standpoint, it is interesting that the wire magnetic and structural properties can be tuned by applying specific annealing treatments to enhance these effects. In the present paper we analyze the magnetization processes under stress in wires with small positive magnetostriction and discuss the potential of applications in wireless sensors for non-destructive testing of polymer composite materials to measure the internal stress/strain.
The microwires are glass-coated ferromagnetic and have a very specific magneticanisotropy. The magnetization process is characterized by single domain wall propagation which happens abruptly when the external field exceeds the nucleation field. Then, a sharp voltage pulse is generated which is characterized by high frequency harmonics. The amplitude of these harmonics may sensitively depend on various stresses: tensile, compressive and twisting.
The detection of high harmonics is possible with enhanced signal-to-noise ratio since the common noise and 1/f noise are greatly suppressed at high frequencies. The harmonic amplitude depends on external parameters, such as stress, strain and temperature. Therefore, these wires canbe used as wireless sensors with remote interrogation and can be placed on the surface or insidematerials.
Scientific adviser - Ph. D. Panina Larisa Vladimirovna