Optimization of tunable GHz micro-antennas based on Giant magnetoimpedance

• Published in: Journal of magnetism and magnetic materials 2019-01, Vol.469, p.289-295
• Main Authors: Archilla, D., Moya, A., Hernando, A., Marín, P.
• Format: Article
• Language: English
• Subjects: Amorphous materials; Anisotropy; Antennas; Dipole antennas; Giant magnetoimpedance; Magnetic anisotropy; Magnetic fields; Magnetic permeability; Magnetic properties; Magnetostriction; Microwave detectors; Microwaves; Optimization; Stress relaxation; Tunnels
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2018.08.049

•Amorphous magnetic microwires have been annealed between to tailor its microstructure.•Microwire length influence on the scattering coefficient of GHz waves has been studied.•The maximum scattering, occurs at the antenna resonance.•Low frequency magnetic field modifies scattering by means of giant magnetoimpedance.•Maxima effect for the highest longitudinal anisotropy but lower electrical resistivity.•The observed effect is useful for new contact-less current and temperature sensors. The unique magnetic properties of amorphous magnetic microwires (AMMW), in particular its interaction with microwaves by means of Giant Magnetoimpedance effect and its magnetostrictive character allow the development of tunable GHz micro-antennas useful as contactless sensing elements with applicability in many fields including biomedical. The possibility of using a single AMMW for this purpose demands the optimization and control of its electrical and magnetic properties in order to adapt them to our needs. In this work we study the changes on electrical resistance and magnetic permeability due to the stress relaxation and to the nanocrystallization induced by thermal treatments in AMMW of composition (Fe2.25Co72.25Si10B15), obtaining important variations in the sensing capability.