A comprehensive role of co-doping (Ce, Al) in dielectric, magnetic, and optical properties of NiO for its efficient use in magneto-optical and spintronics device applications

The crystalline NiO is prepared within the configuration Ni_1-xCe_xAl_xO (x = 0.00, 0.05, and 0.1) using a hydrothermal process. XRD and SEM analyses were conducted to examine the crystal structure and morphology of samples which reveals highly crystalline nature and uniform morphology, respectively. UV-spectra confirms the optical band gap lies in the range of 1.63–3.41 eV. The pristine NiO has a band gap of 3.42 eV which lies in the insulating properties range, while the insertion of co-dopant concentration causes to reduction of the band gap up to 1.63 eV which lies in the semiconducting properties range that ensures the higher electronic conduction. The PL spectra show that the luminescence intensity is highly reduced with the insertion of co-dopant ions in the NiO lattice which is the confirmation of higher sensitivity. Raman spectra reveal the formation and purity of the samples due to the non-existence of secondary Raman modes related to the Ce and Al dopants and are well-matched with XRD results. The magnetic measurements reveal the enhancement in remanace magnetization and saturation magnetization with the reduction in coercivity and square ratio showing that the doping of Ce and Al into NiO is influencing its antiferromagnetic nature. NiO may be showing altered magnetic characteristics with the possible contribution from ferrimagnetic or ferromagnetic phases, as the dopant affects the magnetic interactions. Dielectric measurements reveal the increase in capacitance, conductance, energy dissipation, energy storage, and decrease in resistance with the increase in co-dopant concentrations. Based on the obtained results, NiO with 10 % (Ce, Al) co-doping is a suitable candidate for efficient use in magneto-optical and spintronics device applications.