Modern Physics Letters B

The present review is aimed to understand the Rashba and Dresselhaus effects from the first-principle calculations. A brief overview of first-principle density functional theory (DFT) and its global acceptance have been discussed. The discussions of the Rashba–Dresselhaus splittings, spin textures and understanding the effects from first-principle DFT calculations have been highlighted. Rashba and Dresselhaus effects have gained much attention in recent era for their highly promising applications in spintronics. In the presence of spin-orbit coupling and inherent non-centrosymmetry, while BiTeCl, TiS₂Se, rhombohedral CsPbF₃ and BiCoO₃ compounds show large values of Rashba parameter (${\alpha }_R)$ of $\sim 1.90$, 1.10, 1.05 and 0.74eVÅ, respectively, the single-layered semiconductor nanostructure InSb, rhombohedral BiFeO₃ and Ag₂BiO₃ systems however depict promising values of Dresselhaus parameter (${\alpha }_D)$ of $\sim 2.20$, 0.50 and 0.15eVÅ, respectively. The future of Rashba–Dresselhaus effects and their advancements in spintronics have also been enlightened in this paper. We believe that this study will not only help to understand the Rashba–Dresselhaus effects from first-principle calculations, but can also augment their applications in next generation spintronic devices.

Vacuum forming is used to manufacture large molded parts. As forming conditions have a significant effect on the dimensional accuracy, these should be determined accordingly. In this study, a geometric nonlinear creep analysis of polymethyl methacrylate (PMMA), which is a common thermoplastic resin, was carried out at the target temperature of 393.15K and target strain of approximately 50% for vacuum forming. The proposed fractional differential viscoelastic model was extended to a three-element model, consisting of a single hyperelastic spring and two fractional differential (FD) models. It was further extended by time–temperature superposition (TTS) for thermo-viscoelastic analysis. The model determined all material constants by measuring the temperature/frequency sweeps at small strain amplitudes of 0.01% using dynamic mechanical analysis (DMA). Numerical analysis confirmed the validity of the proposed method through creep and stress-relaxation tests by DMA at the target temperature/strain. The results demonstrated that the finite element analysis constructed using the proposed method could predict the mechanical properties during vacuum-forming-oriented creep tests. These results are expected to provide important insights into the complex mechanical behavior of PMMA, which varies with the temperature and strain rate.

This paper presents a model of a doubly clamped electrically actuated microbeam, which is a commonly used structure in microelectromechanical systems (MEMS). The model is based on Euler–Bernoulli beam theory and includes the effect of electrostatic forces on the beam’s deflection. The electric field is modeled using the parallel plate capacitor model, and the deflection of the beam is calculated using the Galerkin method. The behavior of a microbeam subjected to the van der Waals force, which is a weak intermolecular force that arises from the interaction between the beam and a nearby surface. The microbeam is modeled using the Euler–Bernoulli beam theory, and the van der Waals force is modeled using the Lennard–Jones potential. At the last we study the model of MEMS based on multi-walled carbon nanotubes (MWCNTs). MWCNTs have unique mechanical, thermal, and electrical properties, which make them ideal for use in MEMS applications. The approximate solution of the developed models is found by using homotopy perturbation based Aboodh transformation (HPATM). HPATM is a mathematical method used to solve nonlinear equations by converting them into linear forms. This approach involves introducing a small parameter and applying perturbation theory to obtain a solution in a series form. The method’s accuracy is defined based on the existing literature because its solution matched the variation iteration-based Laplace method. Also, we compared its results with the finite difference method. The validity of the stability analysis is further established by examining the stability in the vicinity of the fixed points. Sketches are made of the phase portraits close to the equilibrium points.

Nowadays, there is great attention given to solar collectors (SCs) for their important applications based on the advantages of nanotechnology and solar radiation. Hybrid nanofluid (HNF) is our first option due to its thermophysical properties that help in improving the overall performance, unlike other nanofluids. This paper gives a detailed novel analysis of SCs with the existence of Newtonian, power-law HNF in unsteady conditions and a three-dimensional model under the consideration of Brownian motion and thermophoresis parameter. In this research, the group transformation method (GTM) and similarity transformation steady state fluid dynamics are used to transform the mathematical model into a simpler system. This coupled system of ordinary differential equations with the related functions, dimensionless entropy generation and Bejan number is achieved at two cases of power-law index. The impact of involved parameters on velocity profile, temperature distribution, concentration field, entropy output of the system and Bejan number is depicted prominently by various graphs. The fluid velocity shows improvement with higher values of power-law index and shape factor, while it diminishes with magnetic parameter and Prandtl number. Enhancing the values of magnetic field and shape factor, results in increase of temperature characteristic which decreases with Prandtl number and power-law index. Increment in the concentration ratio parameter leads to maximize the entropy generation, whereas entropy generation diminishes with higher values of temperature ratio and magnetic parameter. The obtained results and the previously published work are compared qualitatively and quantitatively to each other to validate that the applied method is more efficient. It is predicted that the Nusselt number improves by 28.18% when the Prandtl number is taken range $(4\le \mathrm{\text{Pr}}\le 6)$. The percentage of increasing in Sherwood number is noted to be 18.61% for range $(0.1\le N_b\le 0.5)$ of Brownian motion parameter.

Electronic properties of spin polarized antiferromagnetic ACrO₃ (A = La, Y) are explored with Hubbard model using density functional theory (DFT). These two isostructural systems are investigated using the different Hubbard energy and analyzed the hybridization of chromium 3d orbitals and oxygen 2p orbitals and the change in energy bandgaps against the Hubbard energy. The bond length and bond angle affect significantly the orbital contributions of Cr-3d and O-2p electrons for both the system. We noticed that the Cr–O hybridization affects the orbital degeneracy and is substantiated with partial density of states. These results emphasize the contribution of Hubbard energy in correlated electron systems.

The above-mentioned article, published in journal Modern Physics Letters B, has been retracted, after a thorough investigation. It was determined that the references cited in the article were fabricated (references numbers 1 to 5, 29 and 38). The references in question could not be verified in the available literature. This constitutes a severe violation of academic integrity and publication ethics.

Fabricating references misleads readers and undermines the trust in the academic publishing process. As a result, the article has been retracted from the journal. We apologize to the readers and the research community for any inconvenience caused.

The authors of the article have been informed of this decision.

This retraction has been agreed upon by the Editor-in-Chief and the Executive Editor of the journal Modern Physics Letters B. We take the integrity of our publications very seriously and are committed to ensuring the highest ethical standards.

In the present scenario, the production process of various electronic gadgets including industrial products needs a higher cooling system to get its better features. Therefore, this study reveals the radiating ternary nanofluid flow through a wedged stretching surface. The forced convection of an electrically conducting fluid in association with the particle concentration enriches the study. The novelty of the proposed phenomena is due to the consideration of various shapes such as spherical, cylindrical, and platelet shaped solid particles combined with various physical models of electrical and thermal conductivity, viscosity, specific heat, and heat capacitance. The performance of the ternary nanofluid is presented using a carbon nanotube, graphene, and aluminum oxide in the base liquid water. To achieve a system of non-dimensional form of the governing equations, suitable transformations are adopted and further, shooting-based Runge-Kutta fourth-order technique is employed for the solution of this set of equations. Further, the important outcomes are deployed as follows: the combined effect of the nanoparticles and the base liquid augments the fluid velocity as well as the temperature distributions and thermal radiation also overshoots the temperature profile.

This work examines the role of spatial impurity extension (SIE) on a few nonlinear optical (NLO) properties of impurity-doped GaAs quantum dot (QD). The NLO properties considered are the nonlinear optical rectification (NOR), the second harmonic generation (SHG) and the third harmonic generation (THG). The study also includes 1 (GWN) which has been incorporated into the doped QD through additive and multiplicative pathways. The study uncovers the delicate interplay between GWN and SIE which ultimately fabricates the said NLO properties. NOR, SHG and THG manifest red-shift with enhancement of SIE both with and without GWN. The study also shows possibilities of attaining maximum NLO response by prudently applying GWN in a particular pathway. Depending upon the particular NLO property concerned, the presence of noise and its mode of application can either deplete or amplify it to different extents with respect to the noise-free situation.

The main objective of this investigation is to obtain new closed form solutions for the (3+1)-dimensional Bateman–Burgers equation (B–B equation) by the symmetry method and developed Exp-function method (DEFM). The symmetry method is utilized to infer the infinitesimal generators and build the commutation relations. The similarity reductions of the governing partial differential equations are obtained. The governing partial differential equations are reduced to different ordinary differential equations. The ordinary differential equations are solved by using DEFM. The solutions are analyzed numerically to show the behaviors of the solutions. Solution behaviors include the solitary wave solution, the singular wave solution, the kink wave solution, and the anti-kink wave solution.

Non-Newtonian fluids display fascinating and versatile flow behavior, enabling applications in fields where precise control and manipulation of viscosity are required. This paper presents the rheology of Homann stagnation point flow for a Jeffrey fluid containing gyrotactic microorganisms over a biaxially stretching surface. The system of equations is solved numerically using appropriate similarity transformations and conditions. The boundary conditions are set to maintain a fixed physical environment, and the far field values are defined accordingly. The dual solutions are found and expressed in terms of relevant quantities, and their behavior is analyzed using graphical representations via bvp5c. Stability analysis is conducted as well. The model is extended to study the behavior of Jeffrey nanofluids under the influence of various physical phenomena such as thermophoresis, Brownian motion, Ohmic heating, heat source/sink, radiation, and chemical reaction. The model presented in this paper can help researchers predict and optimize the behavior of such systems for a range of industrial and biomedical applications. It is observed that when the smallest eigenvalue is positive, the disturbance initially decreases, and the flow is stable, otherwise unstable. The stretching/shrinking parameters affect the flow field and boundary layer characteristics, leading to changes in the skin friction forces and an increase in the skin friction coefficient. Moreover, the Peclet number augmented the concentration of microorganisms due to gyrotactic bioconvection for first and second solutions, whereas bioconvective Lewis number shows an opposite trend. The comparison of the present results, as a simplified case, with existing literature demonstrates good agreement.

Hybrid nanofluids have emerged as a promising field of research in recent years, finding applications in various industries and sectors. The entropy generation and impact of an inclined magnetic field on a water-Ethylene Glycol (50:50) mixture-based nanofluid over a poignant thin needle has been investigated under slip conditions. The flow is swotted using thermal and velocity slip boundary conditions. The numerical effects of an inclined magnetic field on the flow of ferrous and aluminum oxide nanoparticles in a hybrid nanoliquid with as base fluids have been examined. The non-dimensional ODEs along with boundary conditions are solved by numerical technique based on the Runge–Kutta fourth-order method. Velocity profile has been analyzed for the magnetic parameter, inclined angle and volume fractions. The Bejan number provides insights into the balance between heat transfer and entropy generation in a system. From the numerical values of skin friction coefficient and Nusselt number, it is analyzed that ${\mathrm{\text{Al}}}_2$O₃ possesses 1.01% and 1.06% of high heat transfer rate and high surface drag force than ${\mathrm{\text{Fe}}}_3$O₄. Heat transfer profile has been analyzed for entropy generation and the Bejan number. The applications of hybrid nanofluids are vast, and one specific area where they can be utilized is in horizontal needle systems.

This research employs Monte Carlo simulations to explore the ground state phase diagrams, hysteresis cycles, and magnetization plateaus of hexagonal boron nitride-like system. Specifically, the ground state phase diagrams are meticulously analyzed with respect to the crystalline field (D), exchange coupling parameter ($J_{AB}$), and external magnetic field (H), and are presented on the ($D,H$), ($D,J_{AB}$), and ($J_{AB},H$) planes. The study observes various stable spin configurations for different parameter values. Furthermore, this investigation delves into the behavior of sublattices of the magnetization plateaus, under the influence of exchange coupling parameter ($J_{AB}$), temperature (T), and the crystalline field (D). The outcomes of this study hold significant implications for the development of magnetic materials for diverse applications.