Tailoring ferromagnetic and dielectric properties in ZnO via (Eu, Co) doping for spin-based electronic devices

Abstract

The development of doped materials is essential for spin-related storage electronics, especially new magnetic nanoparticles that have 100% spin polarization at ambient temperature. This characteristic is seen in several oxide-based semiconductor compounds. In this work, we examine the optical, dielectric, magnetic, and structural characteristics of (Eu, Co) co-doped ZnO nanoparticles (NPs) that were created using the sol–gel technique. The effective integration of Eu and Co ions into the ZnO lattice is confirmed by Fourier Transform Infrared Spectroscopy (FTIR), as shown by distinctive vibrational modes (616, 781, 994, 1112, 1648, 2352, 3502, and 2352 cm⁻¹) and absorption bands. Significant changes in the electronic structure are shown by the consistent variation in bandgap energy with increasing dopant concentration (3.35 eV, 3.36 eV, 3.39 eV, and 3.47 eV for pure ZnO, 5% Eu-doped ZnO, and (Eu, Co) co-doped ZnO (1 and 3%)), as revealed by UV–Vis spectroscopy and Tauc plot analysis. Co-doping affects the dielectric constant (ε_r), dielectric loss (ε″), and AC conductivity (σ_a.c.), according to dielectric measurements. Space-charge polarization (SCP) and rotational dielectric polarization (RDP) are responsible for the polarization effects. According to the frequency-dependent study, co-doping improves the material’s dielectric qualities, which makes it appropriate for energy storage purposes. Room-temperature ferromagnetism (RTFM) in co-doped ZnO is demonstrated by magnetic characterization using magnetization-field (M-H) loops, field-cooled (FC), and zero-field-cooled (ZFC) measurements. A highest value of 0.651 emu/mol at 176 Oe for 5% Eu and 5% Co-co-doped ZnO. An adjustable Curie temperature (Tc) between 328 and 390 K is confirmed by Arrott plots, which also corroborate the observed magnetic behavior, which is caused by carrier-mediated exchange, binding magnetic polaron (BMP) interactions, and defect-induced magnetism. According to our research, ZnO functional characteristics may be tailored by regulated Eu and Co co-doping, which makes it a viable option for spintronic, dielectric, and optoelectronic devices.