Modulation of Room-Temperature Ferromagnetism in Copper Oxide Thin Films by Magnetic Field-Assisted Annealing

This article demonstrates the effect of magnetic field-assisted annealing on the magnetic and structural properties of the sol-gel-derived copper oxide films grown on n-Si substrates. The samples were annealed at 450 °C with and without the presence of an external magnetic field. The comparison of XRD and FESEM results of the annealed samples under three different magnetic fields of 280, 400, and 520 G show that the particle sizes of the CuO films were increased with the increase in magnetic field during thermal annealing. The presence of magnetic field during annealing also modulates reflectance characteristics of the film which can be explored for various optoelectronic applications. Most interestingly, CuO films exhibit ferromagnetic characteristics which can be modulated by varying the externally applied magnetic field during the annealing of the samples. The obtained retentivity and coercivity values of annealed samples in the presence of magnetic field vertically downward are 1.84 x 10
^-2
emu/gm and 280.60 Oe, respectively. These are significantly higher than the values of thermally annealed samples.