Magnetic impedance of structured film meanders in the presence of magnetic micro- and nanoparticles

The magnetic impedance (MI) of film elements in the form of meanders with a [Fe19Ni81]/Cu]$_4$/Fe19Ni81/Cu/[Fe19Ni81/Cu]$_4$/Fe19Ni81 layered structure and variable geometry is studied. For the best meanders (having a maximal MI of up to 125% and an MI maximal sensitivity of about 30%/Oe), the influence of stray magnetic fields is determined. The stray fields are produced by spherical iron particles 500 $\mu$m in diameter and ferrofluids containing iron oxide nanoparticles. The feasibility of detecting intricately configured stray fields from a set of ferromagnetic spheres arranged on the surface of an MI element is demonstrated. The sensitivity of film meander MI elements to nonuniform external magnetic fields is simulated. The results of this work may be helpful in developing special-purpose magnetic sensors intended for micropositioning, nondestructive testing, and biomagnetic detection.