International Journal of Modern Physics B

The multiferroic properties of ion-doped hexagonal and orthorhombic YFeO₃ (YFO) nanoparticles (NPs) are studied theoretically. The magnetization $M_s$ in h-YFO NPs increases, whereas for o-YFO NPs it decreases with decreasing NP size. In the dielectric constant (DC) both h- and o-YFO have a peak around $T_{C1}\sim 450$ and 460 K, respectively, but only in h-YFO an anomaly appears at $T_{C2}\sim 300$ K in the DC and the polarization which could be connected with a possible $P{6}_{3}mc$–$P{6}_{3}cm$ phase transition. The polarization in pure and Bi-doped o-YFO NPs increases with increasing magnetic field. $M_s(x)$ is studied by doping of a o-YFO NP with Ti${4+}^{}$ ions at the octahedral Fe${3+}^{}$ sites. $M_s(T)$ in undoped YFO shows a small kink at $T_{C1}\sim 450$ K, whereas in the doped YFO it shows at $\sim$480 K. By different ion doping on the Y or Fe sites in YFO there is a transformation from the h- to the o-phase or vice versa. In Mn-doped o-YFO a spin-reorientation transition appears. The bandgap of h-YFO is smaller compared to that of o-YFO.

Advances in nanoscience and technology acquired the significance of the nanofluid in novel functional polymers like fibre insulation, geothermal system and chemical catalytic reactors. Inspired by the above applications, an innovative mathematical model is established for radiative nanoliquid flow and is engendered due to stretching sheet with inclined magnetic field which is immersed with nanoparticles. Joule dissipation and exponentially-based heat source/sink effects are employed in the present phenomenon under the heat constraints. The governing equations, which describe the flowing nanofluid, are transformed into invariant dimensionless equations with suitable similarity quantities. With the adoption of a shooting scheme with Runge–Kutta-45, the resultant equations are numerically simplified. The impact of several converted dimensionless elements on physically interesting values is depicted visually. The current analysis is validated through comparison with some selected related literature, which shows a positive correlation. The nanoparticle thermal conductivity is raised for an increased value of the thermal radiation, thermal viscosity and heat source to propel temperature profiles. The heat flux gradient significantly affects the heat propagation all over the flow regime.

This paper adopts the rational extended sine-cosine and cosh-sinh methods to construct the Bogoyavlenskii equation’s exact solutions. To the best of our knowledge, the Bogoyavlenskii equation has not been investigated by aforementioned techniques. In this paper, we find the precise traveling wave solutions of the Bogoyavlenskii equation. Finally, 3D and 2D graphics of the obtained solutions are illustrated for the applicability and reliability of the proposed strategy for various special values.

In this study, we will implement new bright and dark perceptions for the solitary wave solutions to the modified nonlinear Schrödinger equation. The achieved solutions will describe new vision of the following forms. The first form is the rogue wave modes for a derivative nonlinear Schrodinger model with positive linear dispersion which describe the propagation of rogue waves in ocean engineering as well as all similar waves such as dynamics waveguides that have unexpected large displacements. The second form is the waves which occur only in the regime of positive cubic nonlinearity. The third form is the waves that also occur in the regime that coincides exactly with the existence of instabilities of plane waves. The fourth form is the long-wave limit of a breather (a pulsing mode). Two famous different schemas are involved for this purpose. The first schema is the solitary wave ansatz method, while the second schema is the extended simple equation method. The two schemas are implemented in the same vein and parallel to construct new perceptions to the soliton solutions of this model. A comparison between the obtained new perceptions with the old perceptions that were realized before they have been documented.

The effects of energetic electron and proton irradiation on graphene-based devices were investigated. The focus of the study was on the electrical properties of graphene devices exposed to electron and proton beams. Field-effect transistors (FETs) were fabricated using graphene and then irradiated by high-energy electrons and protons of 40 keV that are comparable to the aerospace radiation environment. The deterioration of electric properties, especially the output and transfer characteristics, can be explained by the change of graphene lattice. The Raman spectra confirm the slight lattice deformation after electron irradiation and the structural damage after proton irradiation. Through comparison, it is also found that the proton irradiation will induce more severe influence on the devices than electron irradiation, due to the larger effective interaction radius of the proton.

Considering that the graded structure could generate an electric field, the structure and optoelectronic properties of ${\mathrm{\text{Ga}}}_{1-x}$${\mathrm{\text{Al}}}_x$N superlattice nanowires are considered via first-principles. The structural stability and optoelectronic properties of single-component and component-graded nanowires are discussed. For ${\mathrm{\text{Ga}}}_{1-x}$${\mathrm{\text{Al}}}_x$N superlattice nanowires, the formation energy decreases with increasing Al composition, resulting in a structure that tends to be stable. The ${\mathrm{\text{Ga}}}_{1-x}$${\mathrm{\text{Al}}}_x$N superlattice model is more stable and the bond length changes more dramatically in the superlattice structure with bigger component divergence. The bandgap $E_g$ increases with increasing Al composition. The direct bandgap of ${\mathrm{\text{Ga}}}_{1-x}$${\mathrm{\text{Al}}}_x$N superlattice nanowires is also affected by the nanowire sublayers. The absorption coefficient tends to increase with the increase of Al composition in the nanowires. These studies can serve as the basis for the preparation of ideal materials for deep ultraviolet photocathodes and improve the optoelectronic properties of deep ultraviolet photocathodes.

We study the dynamics of an inertial active Ornstein–Uhnlenbeck particle self-propelling in a confined harmonic well. The transport behavior of the particle is investigated by analyzing the particle trajectories, steady state correlations and mean square displacement (MSD). The steady state correlation functions for the position as well as velocity are exactly calculated using different methods. We explore how the inertia affects the dynamical behavior, when the particle is confined in a harmonic trap as well as when it is set free. From the exact calculation of MSD, it is observed that the initial time regimes are ballistic for both harmonically confined particle and free particle, whereas the long time regimes are diffusive for a free particle and nondiffusive for a harmonically confined particle. One of our interesting observations is that the harmonically confined particle gets more and more confined with increase in the self-propulsion time or activity time of the dynamics and finally it gets trapped for very large value of the self-propulsion time. For a free particle, the velocity correlation decays by the complex interplay between the inertial time scale and the self-propulsion time scale of the dynamics. Moreover, decorrelation in velocity happens only when these two time scales are of equal order.

The applications of nanofluids (NFs) have been comprehensively explored in current years, as they have abundant potential for technical progress and more prominently offer assistances that can be associated with the applications of NFs for several determinations. Nanotechnology can be applied in various technological fields such as medicine, information technologies, food safety and novel materials. Here, novel properties of entropy generation in a mixed convective magneto flow of a Sutterby nanomaterial to an extended surface is scrutinized. Nanofluid model comprises Brownian motion and thermophoresis aspects. The expression of energy depends upon the phenomenon of viscous dissipation and thermal radiation. We formulated the Bejan number and entropy generation. To reduce PDEs into nonlinear ODEs, we use transformation of variables and then the resultant system is solved by bvp4c technique. The influence of the parameters involved, such as thermal radiation, chemical reaction parameter, diffusive variable, magnetic parameter, thermophoresis parameter and Schmidt number for temperature, concentration as well as Bejan number, entropy generation are inspected through tables and graphs.

In the recent decades, the increasing energy demands and its applications have seen the focus shifting to the hybrid nanofluid flows but so much is still left to be investigated. This analysis is executed to explore the hydro-magnetic flow to investigate the incompressible flow and heat transfer towards a stretching surface with velocity and thermal slips. The scaling similarity transformations are created using Lie group analysis and employing these to convert nonlinear partial differential equations to the nonlinear ordinary differential equations. Here, after converting equations from dimensional to non-dimensional, we will use the BVP4C solver (MATLAB) for plotting the graphs to analyze how distinct non-dimensional parameters affect the skin friction and Nusselt number transfer rate, case 1 graphene + CNT + aluminum oxide with base fluid as water and case 2 magnesium oxide + zirconium oxide + copper oxide with water as base fluid, here taking nanoparticles without different shapes. The hybrid nanofluid temperature profile has mixed behavior, and the velocity profile increases when M rises. The hybrid nanofluid temperature profile curvature has composite behavior when $Pr$ rises. The link between several independent or predictor variables and one dependent or criterion variable has been examined using multilinear regression analysis (MLR). When coefficient values for many variables are subject to change, it can forecast a wide range of outcomes.

Thin films of pure and Mg-doped ZnO (Zinc Oxide) were successfully elaborated on glass substrates using the sol–gel technique. X-Ray diffraction patterns show that all grown films have good crystallinity and a hexagonal wurtzite structure, the (002) direction is the most preferred for thin-film growth. Atomic force microscopy (AFM) analysis showed that the surface is homogeneous and more compact with little change in surface morphology with increasing Mg doping rate, which agreed with the crystallite sizes obtained from the XRD results. The structural parameter “$a$” measured and calculated using functional density increases while “$c$” decreases. The electronic and optical bandgap and transmittance improve by increasing the concentration of Mg. The physical origin of the energy gap bowing parameter is investigated using the Zunger approach, which examines the microscopic origins of the energy bandgap bowing. In contrast, the reflectivity and electrical conductivity are reduced with increasing concentration of Mg. The experimental and theoretical results have the same tendency therefore, the Mg-doped ZnO (ZnO:Mg) is an essential candidate material for thin films in many optoelectronic devices.