Microstructural and magnetic properties of rGO/MnFe2O4 nanocomposites; relaxation dynamics

In the present investigation, nanocomposite (NC) of reduced graphene oxide (rGO) and manganese ferrite (MnFe2O4) with three different (rGO/MnFe2O4) weight-ratio of rGO have been synthesized using a simple and efficient one-step hydrothermal route. The crystallinity, morphology and magnetic studies were conducted using X-ray diffraction (XRD), confocal Raman imaging and vibrating sample magne-tometry (VSM). Detailed ferromagnetic resonance (FMR) studies were performed in the field-sweep mode at different applied frequencies ranging from 5 to 30 GHz using a vector network analyzer (VNA). We have realized a nano-composite layer of rGO/MnFe2O4 NC on top of coplanar waveguide (CPW) transmission lines to perform FMR experiments. The largest ferromagnetic resonance (FMR) absorption of -28 dB was observed for 0.06 g GO doped MnFe2O4 at the 22 GHz frequency. This absorption at FMR is found to be tunable by rGO concentration in manganese ferrite. We have also evaluated various relaxation/damping parameters of the nanocomposites. The experimental values of FMR linewidths were fitted using two micromagnetic models, and hence intrinsic and extrinsic damping parameters were obtained for nanocomposite samples. The damping parameters were observed to influenced by the rGO weight ratio. Therefore the developed nanocomposite can find various applications in the area of microwave monolithic devices and circuits like filters, phase shifters, circulators, etc. (C) 2019 Elsevier B.V. All rights reserved.