Zn-composition-driven electronic and magnetic behavior of Co-based ferrites for spintronic and optoelectronic applications: A DFT+U study

This study examines the magnetic, optical, structural and electronic properties of Zn x Co[Formula: see text]Fe 2 O 4 ([Formula: see text]–1.0, with 0.25 steps) ferrites using DFT calculations with the CASTEP code. The simulated X-ray diffraction (XRD) patterns for these ferrites showed increases in lattice constants (8.301–8.491 Å), d-spacings (2.326–2.461 Å), unit cell volumes (571.994–612.176 Å 3 ) and hopping lengths ([Formula: see text]–7.353 Å; [Formula: see text]–6.004 Å) as the Zn[Formula: see text] content grew. Meanwhile, the X-ray density (5.451–5.233[Formula: see text]g/cm 3 ) decreased with increasing Zn[Formula: see text]. The ferrites exhibited properties typical of direct-band gap semiconductors, with the band gap widening from 1.688 to 2.139[Formula: see text]eV as Zn[Formula: see text] content increased. Density-of-states calculations indicated that these materials exhibit desirable spin polarization, suggesting their potential for spintronics. The Hirschfeld analyses revealed that the magnetic moment and saturation magnetization increased from 4.737 to 4.233 [Formula: see text] and from 112.665 to 97.974[Formula: see text]emu/g, respectively, with increasing Zn[Formula: see text] content. The optical properties of Zn x Co[Formula: see text]Fe 2 O 4 ([Formula: see text] 0.0, 0.25, 0.5, 0.75, 1) fall within the visible spectrum, making them suitable for optoelectronic uses. This comprehensive theoretical work offers valuable insights into the structure-property relationships of these ferrites, highlighting their potential for magnetic and optoelectronic applications, as well as multifunctional uses, due to their advantageous structural, optical, magnetic and electronic properties.