Exploring the structural, magnetic, and optical properties of multifunctional Ni_0.4Mn_0.6Cr₂O₄ spinel chromite toward...

The field of non-linear optics is still progressing and having an impact on various sectors; its potential is especially suitable for optoelectronics and photonics. Herein, a pure-phase spinel chromite Ni_0.4Mn_0.6Cr₂O₄ (NMCO) is successfully synthesized via the sol-gel route. Various characterization techniques are used for analysis, such as room-temperature X-ray diffraction, vibrating sample magnetometry (VSM) and UV-visible/NIR infrared spectroscopy. Structural analysis confirms the purity and indicates the crystallographic cubic phase with the Fd3̄m space group of the studied NMCO sample. Analysis of 3D-electron density mapping reveals that heavier nickel and manganese ions are expected to scatter more X-rays than lighter chromium ions. In a magnetic study, second-order magnetic transition from the ferrimagnetic state to the paramagnetic state occurs at around 39 K. Field-cooled M-H hysteresis measurement at 5 K reveals hard ferrimagnetic behaviour, thus holding great potential for permanent magnet manufacturing. Optical analysis, discussed in terms of absorbance as well as reflectance measurements, reveals the semiconducting behaviour of the studied NMCO sample with a direct optical band gap of around 1.72 eV. Further analysis of the optical constants-including refractive index, extinction coefficient, optical conductivity, and dielectric parameters-was carried out to gain deeper insight into the electronic transitions. The dispersion behaviour is analysed using the Wemple-DiDomenico theoretical approach. The non-linear optical response of the Ni_0.4Mn_0.6Cr₂O₄ material demonstrates considerable potential for its use in numerous non-linear devices, including fiber optics, optical modulators and optical switches.