Materials Science & Engineering

Biography

Biography: Pilar Marin

Abstract

Magnetic amorphous microwires have been extensively investigated in the past two decades. The outstanding soft magnetic properties resulting from amorphous structure and small size make them suitable for a wide application. Their giant-magneto impedance (GMI) behavior has been of much research interest. Recently, these microwires have also been used as precursors for fabricating multifunctional composite materials with electromagnetic functionalities. In this work, we report an experimental study on the microwave modulated scattering intensity for a single Fe2.25Co72.75Si10B15 amorphous metallic microwire. The modulation is driven by applying a bias magnetic field that tunes the magnetic permeability of the ferromagnetic microwire. Furthermore, by using a magnetostrictive microwire, we also demonstrate that the microwave scattering is sensitive to mechanical stresses. In fact, we present a wireless microwave controlled stress sensor. As far as the composites are concerned, the tunable properties specifically refer to magnetic field, stress or temperature dependence of effective microwave permittivity. Composite samples containing magnetic microwires as sensing elements can be irradiated by electromagnetic wave and its response can be characterized by complex effective permittivity in a resonance or relaxation dispersive manner generated by the current distribution, which may depend on the microwire impedance. Due to the existence of GMI effect, the dispersion characteristic of effective permittivity also depends on the external stimuli, such as a magnetic field or stress. The mechanical, magnetic, magneto-impedance and microwave measurements and analyses indicate that our new composites are very promising candidate materials for a variety of self-sensing applications.