In recent months, universities around the world have been forced to cancel courses and close their doors due to the growing coronavirus epidemic. Following the government’s precautions, Algerian students were bound to quarantine regulations for their safety. Thus, they unexpectedly switched to online learning instead of face-to-face learning. Our objective of this exploratory study is to investigate the perceptions of Algerian university students regarding the abrupt transition to online learning amid the COVID-19 pandemic. To achieve this goal, an online survey with closed and open-ended questions was conducted among 380 students from the faculty of chemistry and hydrocarbons (FCH) at the University of BoumerdesAlgeria. The results showed that students have a negative perception of online learning. They are reluctant about this new digital pedagogy and prefer the traditional way of teaching to online teaching during the coronavirus pandemic.

The objective of this work is to employ spin-polarized density functional theory (sDFT) calculations for the exploration of ultrathin magnetic films with large magnetic moments and a strong perpendicular anisotropy. Monolayer films of Fe 1−x Co x (with x = 0, 0.25, 0.5, 0.75, and 1) on Rh(001) were addressed to study their magnetic properties using the all-electron full-potential linearized augmented plane wave (FLAPW) method in film geometry. We studied the magnetic order of these films including structural relaxations of the topmost layers. Fe 1−x Co x monolayer films were found to be ferromagnetic (FM) in a broad range of Co content x with a maximum magnetic moment of 2.8 μ B and of an out-of-plane magneto-crystalline anisotropy of 0.25 meV per magnetic atom at x = 0.5. The sDFT results were mapped onto a classical Heisenberg model, demonstrating FM Fe-Co and Co-Co couplings, while the Fe-Fe interaction is antiferromagnetic on Rh(001). The ordering temperature of the FeCo film was estimated to be well above room temperature (482 K).

Using spin density functional theory (SDFT) calculations, we have studied the magnetic states, including collinear and noncollinear magnetic interlayer coupling, of Fe 1−x Co x ultrathin films sandwiching Rh(001) layers. We found very large values for the interlayer exchange coupling (IEC) in Co/Rh n /Co or (FeCo) m /Rh n /Co structures as compared to, e.g., Ag or Au spacer layers. The IEC oscillates with the Rh spacer thickness showing a transition between strong antiferromagnetic and ferromagnetic coupling between five-and seven-layer thickness of the Rh film. Moreover, depending on the thickness of the FeCo film, a reorientation transition between in-plane and out-of-plane easy axis was found when spin-orbit coupling is considered in the calculations. This result suggests that, for specific arrangements such as (FeCo) 2 /Rh 5 /Co structures, a competition between IEC and magnetic anisotropy of coupled films may result in noncollinear ordering. This possibility was studied with constrained, noncollinear SDFT calculations and the results were mapped onto a classical spin model to explore the richness of spin structures that can arise in these multilayer systems.

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In this work, we introduce a computer model and theoretical approach based on the matching technique to investigate the spin precession and the magnetic properties of an ordered magnetic interface joining two ferromagnetic multilayers of type AB, made of 10 spin slabs, obtained by alternative two spin layers A and B. We simulate, particularly, the coherent magnon transmission through spins’ interface, in multilayered thin films, obtained by shearing a part of the film from the other at an angle of 30∘. The individual and total transmittance of bulk magnons of the thin film, scattering coherently at the shearing interface zone and the localized magnonic spin states, are calculated and analyzed. The transmission and reflection spin modes are derived as elements of a Landauer–Büttiker type scattering matrix. The results highlight the localized spin states on the interface shear domain and their interactions with incident magnons. The evolutions of the magnonic spectra can be presented for arbitrary directions of the incident magnons on the boundary zone, for all accessible frequencies in the propagating bands as well as for the magnetic exchange coupling between each spin A(B) and its adjacent sites and their spin intensity. The results demonstrate the dependence of the magnonic spectra for the perfect multilayered films and at the inhomogeneous domain of the interface shear. The analysis of the spectra illustrates the fluctuations, related to Fano resonances, due to the coupling between travelling magnons and the localized modes in the shear interface domain. The calculated spectra could yield useful information concerning the magnetic parameters of such interface slabs in multilayered films.