Noureddine Bouteldja

Zinc substitution in Cd1−xZnxTe (CZT) alloys emerges as a powerful strategy for engineering their structural, elastic, mechanical, acoustic and thermal properties, thereby enhancing their potential for high-performance optoelectronic and radiation detection applications. In this work, a comprehensive first-principles investigation based on Density Functional Theory, within both the Generalized Gradient Approximation and the Local Density Approximation, is conducted to systematically explore the composition-dependent behavior of CZT across the full concentration range (0 ≤ × ≤ 1) in the cubic zinc-blende phase. The calculated elastic constants satisfy the Born stability criteria for all compositions, confirming the intrinsic mechanical stability of the alloys upon Zn incorporation. A pronounced and continuous increase in the bulk modulus, shear modulus and Young modulus is observed with increasing Zn content, revealing a significant enhancement in lattice rigidity driven by the formation of shorter, stronger Zn–Te bonds and improved bond covalency. Despite this stiffening, CZT alloys consistently exhibit ductile behavior, as demonstrated by positive Cauchy pressures, Pugh ratios well above the critical value for ductility (B/G > 1.75), and Poisson ratios within the range of 0.29–0.37, indicating a favorable balance between strength and deformability. The Vickers hardness shows a systematic increase from 1.89 to 6.66 GPa with Zn concentration, highlighting improved resistance to plastic deformation while maintaining the moderate hardness typical of II–VI semiconductors. Additionally, the moderate elastic anisotropy indicates controlled directional dependence without compromising structural integrity. Concurrently, the monotonic enhancement of the longitudinal, transverse and average sound velocities reflects increasingly efficient elastic wave propagation and improved lattice cohesion. The Debye temperature rises significantly from approximately 163 to 227 K, providing strong evidence of reinforced interatomic bonding and superior thermal stability. Collectively, these results deliver a coherent and in-depth theoretical framework demonstrating that the physical properties of CZT alloys can be precisely tuned through compositional engineering. This tunability, combined with their inherent stability and balanced mechanical performance, positions CZT as a highly promising and versatile material platform. It is well suited for next-generation radiation detectors and advanced semiconductor devices operating, even under demanding mechanical and thermal conditions.

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.

Journal of Nano- and Electronic Physics. Scientific journal. ISSN: 2077-6772. Journal abbreviation: J. Nano- Electron. Phys. No page charges. All articles are freely available on-line. Issued 4 times per year. Publisher: Sumy State University. (Sumy, Ukraine)

This study focuses on investigating the influence of exchange and correlation interactions on the spin polarized electronic structure and magnetic properties of Ga0.75Mn0.25P in the B3 Zinc Blende phase. First-principle calculations were performed by systematically varying the Hartree-Fock (HF) exchange (α) value from 0 to 25% using the onsite exact-exchange functional for the treatment of the correlated electrons. The electronic and magnetic properties unveil that Ga0.75Mn0.25P manifests a half-metallic ferromagnetic behaviour at deferent values of HF exchange. Moreover, as the fraction (α) parameter increases, the band gap increases, leading to modifications in the spin polarized band structures. Additionally, our investigations indicate that exchange and correlation interactions cause an increase in the lattice parameter and volume of the compound. Furthermore, these interactions result in a decrease in the magnetic moments of P and Ga atoms, while the Mn moments increase. These findings provide valuable insights into the behavior of Ga0.75Mn0.25P and offer potential applications in the design of spintronic devices. Це дослідження зосереджено на вивченні впливу обмінних і кореляційних взаємодій на спін-поляризовану електронну структуру та магнітні властивості Ga0.75Mn0.25P у фазі B3 Zinc Blende. Розрахунки першого принципу були виконані шляхом систематичної зміни значення обміну Хартрі-Фока (HF) (α) від 0 до 25% з використанням локального функціоналу точного обміну для обрахунку поведінки корельованих електронів. Електронні та магнітні властивості показують, що Ga0.75Mn0.25P демонструє напівметалеву феромагнітну поведінку при різних значеннях HF-обміну. Крім того, зі збільшенням параметра фракції (α) ширина забороненої зони збільшується, що призводить до модифікацій у спін-поляризованих зонах структурах. Крім того, наші дослідження показують, що обмінні та кореляційні взаємодії викликають збільшення параметра решітки та об’єму сполуки. Крім того, ці взаємодії призводять до зменшення магнітних моментів атомів P і Ga, тоді як моменти Mn збільшуються. Ці висновки дають цінну інформацію про поведінку Ga0.75Mn0.25P для потенційних застосуванняь в дизайні спінтронних пристроїв.