Magneto-optical properties of Cu1−xZnxFe2O4 nanoparticles

• All products present superparamagnetic behavior at room temperature (RT).
• The high Ms and magnetic moment values are attributed to cation distribution change.
• The estimated Eg values for ZnFe2O4 NPs are in accordance with results reported in the literature.
• The greater magnitude of band gap for the coated samples proves the existence of magnetic and nonmagnetic shells.

Zn doped CuFe2O4 nanoparticles (CZF NPs) were synthesized by a citric acid assisted sol–gel auto combustion process. The obtained samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, UV–Vis diffuse reflectance spectra (DRS), and vibrating sample magnetometer (VSM). XRD results confirmed the formation of cubic spinel-type structure with an average crystallite size in the range of 27–33 nm. The variation lattice constants obey the Vegard’s Law. The CZF NPs were evaluated for their magneto-optical characteristics. The CZF NPs exhibit superparamagnetic behavior at room temperature (RT). The average Ms value for CZF NPs is about 57 emu/g. The observed magnetic moments of products are in the range of 1.76–2.49 μB. The small Mr/Ms ratios (maximum 0.22) specify uniaxial anisotropy in the Cu1−xZnxFe2O4 NPs. The high Ms and magnetic moment values are attributed to cation distribution change. The direct optical band gap (Eg) value of CZF NPs was found as 1.42 eV.