Percorrer por autor "Hajji, Ala Ben Abderrazak"
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- A comprehensive study of the structural, magnetic and optoelectronic behavior of Ni0.6Mn0.4Cr2O4 chromite for magneto optical devicesPublication . Hajji, Ala Ben Abderrazak; Wali, Mouna; Dhahri, Radhia; Dhahri, Essebti; Mariano, José; Jemmali, MosbahChromium-based spinel oxides have recently gained popularity in commercialisation field owing to its suitability in optoelectronic applications. Pure phase Ni0.6Mn0.4Cr2O4 spinel chromite nanopowder with a cubic structure and (Fd3m) space group was successfully synthesised via the sol gel route. Magnetic and optical characterisation were performed by the vibrating sample magnetometry (VSM) and UV–Visible spectrophotometer leading to determine some intrinsic parameter such us Curie Temperature (TC) and optical band gap energy (Eg). The thermal variation of magnetization at a field of 150 Oe gives rise to a magnetic phase transition from the ferrimagnetic state to the paramagnetic one at a Curie temperature of 47 K. The M − H hysteresis loop carried out at 5K gives rise to hard ferrimagnetic behaviour of the studied sample with coercive field of 9967.72 Oe confirming its suitability in the permanent magnet manufacturing. The spectral behaviour of absorption gives rise to a broad visible absorption as well as direct optical gap of 2.14 eV. The refractive index, the optical dielectric constants as well as the non-linear behaviour of the studied compound were discussed. The outstanding results definitely present a high path to significant magneto-crystalline anisotropy as well as powerful luminous efficiency of Ni0.6Mn0.4Cr2O4 making it suitable for the manufacture of devices that combine various optical and magnetic properties.
- MnCr2O4: a promising material with suitable magnetic response for spintronic and magnetic recording devicesPublication . Wali, Mouna; Hajji, Ala Ben Abderrazak; Dhahri, Radhia; Dhahri, Essebti; Mariano, José; Morales, Marco A.; Silva, Rodolfo B. daOver the last few years, a new magnetic nanoparticles system has been elaborated in order to enhance the magnetic feature of spintronic and ultra-high-density recording devices with respect to promoting the anisotropic behaviour and ensuring the magnetic ordering stability. The smart MnCr2O4 chromite compound is becoming more popular these days thanks to its promising potential to create an extra source of anisotropy energy so that it becomes steadily moving toward commercialization referring to its soft ferrimagnetic behaviour and low manufacturing cost. In this research paper, single phase spinel MnCr2O4 chromite compound has been successfully prepared through the use of the Sol-gel method. The room temperature X-ray Diffraction characterisation technique was applied to confirm the cubic crystallographic structure. The thermal magnetization M(T) has been explored at various low applied magnetic fields (100, 300 and 500 Oe) to investigate the spin-glass behaviour of our compound. M(H) measurements have been performed between 5 and 50 K, giving rise to an exchange bias (EB) effect in our material. In this respect the various hysteresis and anisotropy parameters have been respectively determined using a theoretical model as well as the well-known Law to Approach to Saturation (LAS). The effect of temperature on these parameters was tackled. A significant increase of the coercive field from 22.1 Oe to 29.7 Oe was recorded confirming the soft ferrimagnetic behaviour of the examined compound (HC ˂ 628 Oe). These outstanding results, definitely confirm the interesting potential of MnCr2O4 to be invested within the area of spintronic devices manufacturing.
- MnCr2O4: A suitable material with significant optical response for optoelectronic devicesPublication . Hajji, Ala Ben Abderrazak; Wali, Mouna; Dhahri, Radhia; Kammoun, Souha; Dhahri, Essebti; Mariano, José; Jemmali, MosbahIn current high-tech electronics, a power-efficient and compact light source has an essential role to play in the development of non-destructive and non-invasive detection applications as well as for advancing of technological innovation. In this order, an innovative investigation has been taken into consideration in this paper to characterize the optoelectronic behaviour of MnCr2O4 spinel chromite compound based on both experimental and theoretical approaches. The room temperature X-ray diffraction gives rise to a single-phase spinel compound which crystallises in the cubic system with the space group (Fd 3 m). Thanks to the UV-Visible/NIR absorbance and reflectance measurement, the direct semiconducting behaviour (Edg = 2.41 eV) of chromite sample have been verified. The spectral behaviour of absorbance proves that the sample under study exhibit a broad absorption in the visible range. The high localized state density is confirmed by the significant high Urbach energy value that was observed (Eu = 2.86 eV). Various optical parameter such as refractive index, extinction coefficient, dielectric real and imaginary optical permittivity have been analysed to more investigate experimentally the optoelectronic behaviour of the studied sample. Owing to the Wemple Di-Domenico model additional dispersive parameters have been identified. A comprehensive analysis of the crystal field theory based on the theoretical evaluation of the algebraic Racah tensor was taken into consideration on trivalent chromium Cr3+ (3 d3) according to the Oh symmetry site.The demonstrated results are undoubtedly a road to achieving high-power conversion efficiency making our material promising for multitude optoelectronic application.