Room temperature ferromagnetism, optical band gap widening in Mg-doped ZnO compounds for spintronics applications

Abstract

In the present research work, a conventional solid-state synthesis approach was used to synthesize the polycrystalline compound of Mg-doped ZnO (Zn1-xMgxO with x = 0–0.12). The XRD analysis reveals that Mg-doped compounds have been crystallized in a single hexagonal phase. The SEM analysis revealed that these compounds are constituted with microscopic spherical particles with a size range of 1–3 μm. Raman scattering spectra of these compounds displayed a blue-shift of the Raman active E2 (low) mode attributed to the vibration of zinc atom in wurtzite ZnO, indicating Mg ions were substituted successfully into the ZnO lattice. Optical measurements revealed that the optical band gap enhanced from 3.12 to 3.17 eV, while the transmittance value improved from 87% to 96% as the Mg doping percentage is increased. The magnetization (M) versus applied field (H) measurements, done at 300 K reveals that the undoped ZnO compound exhibits weak ferromagnetic behavior, whereas all Mg-doped ZnO compounds show a strong ferromagnetism with coercivity ranging between 85Oe≤Hc≤1482Oe, and with the highest saturation magnetization of 0.255 emu/gm for 12% Mg-doped sample.