Noureddine Hacini

The search for high-performance spintronic materials motivates the exploration of Heusler alloys with unconventional electronic properties. Using density functional theory with Hubbard correction (DFT+U, U = 4 eV), we investigate X2MnGa (X = Ti, Ir) alloys, which stabilize in the ferromagnetic L21-type structure with strong thermodynamic stability. Electronic structure calculations reveal contrasting behaviors: Ti2MnGa transitions from a metallic L21-type phase to a spin gapless semiconductor (SGS) in the XA-type, while Ir2MnGa exhibits gapless half-metallicity behavior in the L21-type but becomes half-metallic in the XA-type. The magnetic properties are governed by spd hybridization between Mn-3d and X-d/Ga-p states, which stabilizes ferromagnetism and tailors electronic states near the Fermi level. The Hubbard U correction proves essential for accurately describing the correlated Mn-3d electrons. These alloys combine structural stability with tunable electronic and magnetic properties, offering a promising platform for spin-polarized transport in next-generation spintronic devices.

ZnO thin films were synthesized on silicon and glass substrates using the plasma-enhanced chemical vapor deposition (PECVD) technique. Three samples were prepared at substrates temperatures of 200, 300, and 400 °C. The surface chemical composition was analyzed by the use of X-Ray Photoelectron spectroscopy (XPS). Structural and morphological properties were studied by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties were carried out by UV-visible spectroscopy. XPS spectra showed typical peaks of Zn(2p3/2), Zn(2p1/2), and O(1s) of ZnO with a slight shift attributed to the substrate temperature. XRD analysis revealed hexagonal wurtzite phases with a preferred (002) growth orientation that improved with temperature. Calculation of grain size and dislocation density revealed the crystallization improvement of ZnO when the substrate temperature varied from 200 to 400 °C. SEM images of ZnO films showed textured surfaces composed of grains of spherical shape uniformly distributed. The transmittance yields are reaching 80%, and the values of the band-gap energy indicate that the ZnO films prepared by PECVD present transparent and semiconducting properties.