Flexible YIG-poly(vinyl-alcohol) magnetic composite films for microwave applications

Flexible magnetic composite films based on yttrium iron garnet (YIG) and poly(vinyl alcohol) (PVA) with composition x YIG:(1 − x )PVA (0 ≤ x ≤ 0.63 wt) were successfully obtained by facile casting technique. The structure, magnetic, and microwave absorption properties of YIG/PVA films were characterized by XRD, Raman spectroscopy, FTIR, vibrant sample magnetometry (VSM), and ferromagnetic resonance (FMR) techniques. XRD, Raman and FTIR analysis confirmed the complete synthesis of YIG/PVA composites, without any chemical interaction between particles of YIG and PVA matrix. VSM experiments revealed a ferrimagnetic ordering in composite films with small in-plane anisotropy; their specific magnetization increases linearly with the YIG content. YIG/PVA films exhibit an effective imaginary microwave permeability of μ max ″ ~ 0.1–0.5, as determined by FMR measurements. Numerical simulations of the FMR spectra showed that the large FMR linewidth of Δ H pp ∼ 80 kA/m is associated with the shape anisotropy and the interactions between YIG particles. A small effective field of H eff = 20–25 kA/m was originated by the confinement of YIG particles within a PVA matrix into a two-dimensional geometry. The combination of flexibility, magnetic, and microwave properties makes of YIG/PVA films suitable materials for microwave absorption applications.