Synthesis, Structural, Dielectric, Magnetic and Magnetodielectric Properties of Graphene Quantum Dots (GQDs) Decorated ZnFe₂O₄ Hybrid Nanocomposite (GQD-ZHN)

A graphene quantum dot (GQD)-decorated ZnFe₂O₄ hybrid nanocomposite [GQD-ZHN] was synthesized using the sol–gel technique. In the X-ray diffraction (XRD) analysis, a cubic spinel structure was identified with the space group Fd-3 m. Fourier-transform infrared (FT-IR) analysis revealed the vibration bands of the samples, while the existence of GQDs in GQD-ZHN was confirmed by the Raman spectra. Field emission scanning electron microscopy (FESEM) provided insights into the microstructural morphological topology of the surface. The dielectric properties of GQD-ZHN were analysed with respect to their dependence on frequency and temperature and explained by Maxwell–Wagner-type polarization. The frequency-dependent ac conductivity (σ_ac) followed Jonscher’s power law and investigated the dynamics of ion hopping in GQD-ZHN. Impedance and modulus spectroscopy were used to further evaluate electrical characteristics such as relaxation time (τ). Nyquist plots have been used to estimate grain and grain boundary contributions. The GQD-ZHN exhibited superparamagnetic properties at room temperature. At room temperature, GQD-ZHN exhibited a strong magneto-dielectric coupling (MD) and showed negative magneto-dielectric properties in low-frequency regions. These properties of GQD-ZHN enable it to be used as a potential application in microelectronic systems, spintronics and memory devices.