Exchange-coupled hard-soft ferrites; A new microwave material

During the past decade, hexaferrite has become an important candidate for a variety of microwave and millimeter-wave devices due to their large uniaxial magneto-crystalline anisotropy and high saturation magnetization. The goal of this investigation is to synthesize BaFe12O19/Y3Fe5O12 (Barium hexaferrite/ Yttrium Iron Garnet-BaM/YIG) hard-soft ferrite nanocomposites (NCs) as an advanced microwave material. A detailed microstructure and magnetic properties of these nano-composites were investigated using various techniques; viz. X-ray diffractometry (XRD), vibrating sample magnetometry (VSM), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). With recent advances in nanostructure synthesis techniques, we have realized a thin nano-composite layer on top of coplanar waveguide (CPW) planar transmission lines to design microwave notch-filters. Using a vector network analyzer we have checked the device operation from X-to Ka-band through ferromagnetic resonance (FMR) spectroscopy. The FMR linewidth (device bandwidth) is observed to be tunable with (BaM)(1-x) (YIG)(x) nanocomposite from 2 kOe (900 MHz) for pure BaM (x = 0) to 0.2 kOe (90 MHz) for pure YIG (x = 1). Various mathematical models were employed to fit the experimentally observed FMR linewidth (Delta H) data to yield intrinsic and extrinsic damping parameters as a function of 'x' value in (BaM)(1-x) (YIG)(x) nanocomposite. (C) 2017 Elsevier B.V. All rights reserved.