Exchange couplings calculation in Sr2CrNO6 (N = Os, Ir) Double Perovskites: Monte Carlo simulation

O. El Rhazouani,A. Slassi,Y. Ziat,A. Benyoussef 한국물리학회 2017 Current Applied Physics Vol.17 No.7

Exchange couplings in Sr2CrNO6 (N ¼ Os, Ir) Double Perovskites (DPs) have been calculated numerically by using a Monte Carlo Simulation (MCS) in the frame work of Ising model by means of a relation between internal energy per site and magnetization per site. Two model parameters a and a0 have been proposed for Sr2CrOsO6 and Sr2CrIrO6, respectively. The exchange couplings have been computed by varying a and a0 through a MCS to find their values corresponding to the transition temperature 725K specific to Sr2CrOsO6 and 884K specific to Sr2CrIrO6. The exchange couplings JCr『Os ¼ 『35:201meV, JCr『Cr ¼ 5:452 meV and JOs『Os ¼ 14:873 meV have been obtained for Sr2CrOsO6, while JCr『Ir ¼ 『24:464 meV, J0 Cr『Cr ¼ 2:181 meV and JIr『Ir ¼ 16:730 meV have been obtained for Sr2CrIrO6. Magnetization and magnetic susceptibility have been investigated in both compounds. Internal energy per site has been given.

Nanostructured BaTi1-xSnxO3 ferroelectric materials for electrocaloric applications and energy performance

Benyoussef M.,Mura T.,Saitzek S.,Azrour F.,Blach J.-F.,Lahmar A.,Gagou Y.,El Marssi M.,Sayede A.,Jouiad M. 한국물리학회 2022 Current Applied Physics Vol.38 No.-

Nanostructured BaTi1-xSnxO3 (x = 0, 0.05 & 0.075) were successfully synthesized using the modified Pechini processing method. The phase purity and symmetry were examined by X-ray diffraction and Raman spectroscopy. Tetragonal symmetry was obtained for BaTiO3 (BT) while orthorhombic symmetry for Sn doped BT. BT exhibits an up-shift of the Curie temperature towards high temperatures (TC = 139 ◦C). In contrast, a down-shift was recorded for Sn doped BT. Then, indirect electrocaloric (EC) adiabatic temperature change ΔT and the energy storage performances were determined based on ferroelectric hysteresis loops. Interestingly, large EC responsivity of ΔT/ΔE = 0.81 × 10-6 K m/V was obtained for the BT accompanied with a moderate stored energy of 23 mJ/cm3 but with a high energy efficiency of 67%. The incorporation of Sn in BT was found to broaden the EC responsivity and to improve the energy efficiency up to 90%, recorded for the 5% Sn doped BT.

Monte Carlo study of magnetic properties and critical behavior of Sr2CrMoO6

G. Dimitri Ngantso,A. Benyoussef,A. El Kenz 한국물리학회 2016 Current Applied Physics Vol.16 No.2

We performed the Monte Carlo simulation (MCs) in order to study the magnetic properties and the critical behavior of Sr2CrMoO6. Within this magnetic oxide, the Cr3þ and Mo5þ ions form two interpenetrating ferromagnetic sublattices with opposite spins directions (Cr3 þup and Mo5þdown). The exchange interaction between these sublattices is assumed to be ferrimagnetic. The effects of the system parameters on critical temperatures and as a result on the phase diagrams are shown by using reduced values of parameters. The phase transitions and the magnetic stability are investigated in the framework of Ising model. For specific values of the system parameters, the existence of a compensation point is shown. Furthermore, to investigate the critical behavior, the critical exponents are calculated, they indicate that the compound belongs to a three dimensional Ising universality class. The reduced transition temperature is also found.

Study of the solar perovskites: XZnF3 (X = Ag, Li or Na) by DFT and TDDFT methods

Idrissi S.,Mounkachi O.,Bahmad L.,Benyoussef A. 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.2

In this work, we have applied the density functional theory (DFT) and time-dependent density-functional theory (TDDFT) to study and discuss the different properties of the inorganic perovskites XZnF3 (X = Ag, Li or Na). In fact, we have presented the structural, electronic and optical properties of the Halide Perovskite XZnF3 (X = Ag, Li or Na). Such materials are in great demand for solar cell uses. To conduct this study, we have applied the Quantum Espresso package using the two methods: GGA–PBE and GGA–PBESol. The different lattice parameter a (Å) values have been used to deduce the energy optimum of the perovskites XZnF3 (X = Ag, Li or Na). Besides, the total and partial density of states (DOS) and the band structure of these materials have been illustrated for the two situations: in the presence and the absence of the Spin Orbit Coupling (SOC) approximation. To complete this study, we have presented the optical properties of the XZnF3 (X = Ag, Li or Na) materials. In fact, such properties have been investigated when exploring the real and imaginary parts of the corresponding dielectric function. To reach this goal, we have applied the two approximations: the GGA–PBE and GGA–PBESOL. Our results reveal high transparency of the electromagnetic radiations in the energy range between (0.0 ħω) Ry and (0.25 ħω) Ry. A notable peak of the imaginary part, has been found at about (0.15 ħω) Ry for the studied materials, confirms the transition from the top of valence band to the bottom of conduction band.

The effect of chalcogens-doped with dilation strain on the electronic, optic, and thermoelectric properties of perovskite BaSnO3 compound

Akenoun B.,Dahbi S.,Tahiri N.,El Bounagui O.,Ez-Zahraouy H.,Benyoussef A. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5

The effects of three axial dilation strains and chalcogens-doped BaSnO 3 on the electronic, optic, and thermoelectric properties of perovskite BaSnO 3 compound were carried out using density functional theory. It was found that after applying dilation strain up to 2.5%, the bandgap decreases from 3.149 eV (pure) to 2.18% (2.5% of dilation strain). Moreover, when chalcogens (S, Se, and Te) and 2.5% of three axial dilations occur in the BaSnO 3 compound, the BaSnO 3 becomes a semiconductor with a direct bandgap. Furthermore, the bandgap decreases white the increase of chalcogens elements in BaSnO 3 up to 5.0%. Furthermore, when S, Se, or Te-doped BaSnO 3 with the presence of 2.5% of three axial dilations, the absorption coefficient shifts into the visible region due to the reduction of bandgap which is quite recommended the photovoltaic applications. In addition, the transport properties show that the electrical conductivity increased with increasing temperature in the case of S/Se-doped + 2.5% of dilation strain and it decreases in the case of Te-doped BaSnO 3 + 2.5% of dilation strain due to the increase of collisions between the vibrating atoms and moving electrons, while the thermal conductivity increases with increasing temperature for all studied compounds.

Magnetic Properties of Antiferromagnetic Thin Films with spin S

R. Masrour,M. Hamedoun,E. K. Hlil,A. Benyoussef 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.7

The mean field theory (MFT) and high temperature series expansions (HTSEs) of the magneticsusceptibility are used to investigate the magnetic properties in simple cubic (sc) antiferromagneticwith spins S = 1 and S = 3/2 films by using both the Ising and the XY models. The films consistingof l = 2, 3, 4, 5, 6 and infinite (1) interacting layers are studied up to sixth order series in x = Jwhere = 1kBT , for free-surface boundary conditions. The effects of finite size on the critical-pointbehavior are studied by extrapolation of the high-temperature series. The N´eel temperature TN(l)as a function of the spin layers numbers l is obtained by using HTSEs of the magnetic susceptibilityseries, the Pad´e approximant method and the MFT theory. The critical exponentassociatedwith the magnetic susceptibility is deduced. The N´eel temperatures TN(l) for the l-layers films areestimated from the divergence of the staggered susceptibility with exponents(1) and(2) for theIsing and the XY models, respectively. This is consistent with the basic assumptions of scalinglaws. The shift exponents of the N´eel temperature for the Ising and the XY models, respectively,are estimated.