Spin dynamics investigations of multifunctional ambient scalable Fe3O4 surface decorated ZnO magnetic nanocomposite using FMR

Abstract

Microwave spin resonance behavior of the Fe3O4 surface decorated ZnO nanocomposites (FZNC) has been investigated by ferromagnetic resonance (FMR). Modified hydrothermal method has been adopted to fabricate FZNC samples with Fe3O4 nanoparticles chains were used as seeds in the uniform magnetic field to decorate them on the surface of the ZnO nanoparticles in a unique configuration. Spin dynamics investigation confirms the transition of ZnO from diamagnetic to ferromagnetic as the sharp FMR spectra converts to the broad spectra with Fe3O4 nanoparticles incorporation. A single broad FMR spectra confirms that no isolated Fe3+ or Zn2+ ions exist which is also in agreement with XRD confirming suitable composite formation. Further, the increase in Fe3O4 concentration leads to decrease in g-value which is resulting from the internal field enhancement due to magnetic ordering. Also, various spin resonance parameters were calculated for the FZNC which provides a detail information about the magnetic ordering, exchange coupling and anisotropy. Elemental analysis confirms the presence of Fe and Zn simultaneously and transmission electron microscopy (TEM) image show the presence of Fe3O4 on the grain boundaries of ZnO which has been confirmed by taking high-resolution TEM and electron diffraction patterns on both sides of the interface. These unique structural configuration of the FZNC has tremendous potential in various magneto-optoelectronic, spintronics and electro-chemical applications.

Facile Synthesis, Static, and Dynamic Magnetic Characteristics of Varying Size Double-Surfactant-Coated Mesoscopic Magnetic Nanoparticles Dispersed Stable Aqueous Magnetic Fluids

“…It can be well understood as the larger particle size samples magnetize and demagnetize at lower field due to strong dipolar interactions. This allows the magnetic spins to align in the field direction more easily [19]. The shifting of the resonance peak to a higher value with a decrease in the size of the MNPs can be explained by the magneto-crystalline anisotropy and thermal energy.…”

“…In all the samples, the particles are almost spherical with equisized distribution. The inset Figure 6a shows the HRTEM image of sample A having an interplanar spacing of 0.29 nm, which corresponds to the (220) plane of the spinel ferrite phase [19]. Similarly, the inset in Figure 6b-d shows the HRTEM image of samples B, C, and D, respectively.…”

“…The surfactant is used to prevent agglomeration in the system, and chosen based on the size of the MNPs to provide the desired steric repulsion [18]. Oleic acid is the most commonly used surfactant; it provides a chain length of around 2 nm, which is ideal for the MNPs of average size 10 nm [19]. The choice of carrier liquids is entirely based on the application requirement.…”

“…One of the major advantages of these systems is that the particles in both a dry as well as in a fluid state can be characterized by changing the sample stage [15]. FMR is a very versatile and sensitive instrument, and it can sense the FMR signals in the range 10 14 -10 16 magnetic moments/minute in ordered FM materials [19]. It has a sensitivity of the relaxation times of the magnetically polarizable particles in the range 10 −7 -10 −10 s. Further, it can also perceive the paramagnetic impurities in the material as minor as the ppm level [48].…”

Review on Recent Progress in Magnetic Nanoparticles: Synthesis, Characterization, and Diverse Applications

“…The MNPs size ranges between nano-to-micro scales, show the property of superparamagnetic. When an external magnetic field is applied on these NPs, they show magnetic sensitivity and can interact with these external magnetic fields ( Pathak et al, 2021 ). However, in the absence of external magnetic field shows no magnetism.…”