Rabiu Musah - Profile on Academia.edu (original) (raw)

Papers by Rabiu Musah

Research paper thumbnail of Hydrodynamics of vortex memory system driven by edge-current and boundary magnetization

arXiv (Cornell University), May 5, 2024

In this study, a magnetohydrodynamic model is developed to study the dynamics of vortices driven ... more In this study, a magnetohydrodynamic model is developed to study the dynamics of vortices driven by edge-current. Two modeled equations for fluid and magnetic field variables are each transformed into diffusion equation for vorticity and poisson equation for stream function. A numerical solution method is designed using a simplified Lattice Boltzmann method (LBM). The LBM-D2Q5 scheme is utilized to obtain the numerical solutions for the fluid and magnetic field variables. Understanding the hydrodynamic behavior of systems employed in vortex-based memory systems is crucial for reliability and performance optimization. Based on this motivation, the effect of applied edge-current on the hydrodynamic and magnetic vortex configurations are analyzed through numerical simulations. The impact of the boundary magnetization is also conducted, by varying the strength of the magnetic field at the bottom boundary. The obtained graphical results provide some insights into the design and operation of vortex-based memory systems for next-generation data storage applications.

Research paper thumbnail of MHD flow of blood-based hybrid nanofluid through a stenosed artery with thermal radiation effect

MHD flow of blood-based hybrid nanofluid through a stenosed artery with thermal radiation effect

Case studies in thermal engineering, Apr 1, 2024

Research paper thumbnail of Stark-cyclotron resonance in an array of carbon nanotubes

arXiv (Cornell University), Jun 1, 2015

Using the kinetic approach based on the semiclassical Boltzmanns transport equation with constant... more Using the kinetic approach based on the semiclassical Boltzmanns transport equation with constant relaxation time, we theoretically studied the Starkcyclotron resonance in an array of carbon nanotubes. Exact expression for the current density was obtained. We noted that Stark-cyclotron resonance occurs when the Larmor frequency coincides with the Stark frequency.

Research paper thumbnail of Nonlinear Conductivity in Graphene

arXiv (Cornell University), Oct 23, 2015

We consider the tight-binding approximation for the description of energy bands of graphene, toge... more We consider the tight-binding approximation for the description of energy bands of graphene, together with the standard Boltzmanns transport equation and constant relaxation time, an expression for the conductivity was obtained. We predicted strong nonlinear effects in graphene which may be useful for high frequency generation.

Research paper thumbnail of Influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes under homogeneous axial dc field

Influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes under homogeneous axial dc field

Low Temperature Physics

We present theoretical framework investigations of the influence of temperature variation on the ... more We present theoretical framework investigations of the influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes (CNTs) under the applied homogeneous axial dc field. This study was done semiclassically by solving Boltzmann transport equation to derive the current density of zigzag CNT as a function of homogenous axial dc field and temperature. Plots of the normalized current density versus homogeneous dc field applied along the axis of semiconducting zigzag CNTs as room temperature increases from 293 to 299 K revealed a significant increase in electrical conductivity, whereas in metallic zigzag CNTs, almost constant or a negligible decrease in electrical conductivity is observed. The study predicts semiconducting zigzag CNT as a potential material for temperature sensors since it exhibits a faster response and a substantially higher sensitivity to room temperature changes than the metallic counterpart. The electrical conductivity of metallic zigzag...

Research paper thumbnail of Enhanced nonlinear conductivity due to hot-electron injection in carbon nanotubes

Enhanced nonlinear conductivity due to hot-electron injection in carbon nanotubes

Low Temperature Physics

We have theoretically obtained an expression for the current density in a terahertz field due to ... more We have theoretically obtained an expression for the current density in a terahertz field due to hot-electron injection in carbon nanotubes. The injection modifies the stationary distribution function and leads to a qualitative change in the behavior of the current-voltage characteristics and causes absolute negative conductivity. We compared the current-voltage characteristic behavior at different injection rates and observed a drastic change in the current density and absolute negative conductivity values. We propose that carbon nanotubes with hot-electron injection may be useful for high-frequency applications.

Research paper thumbnail of Heat Transfer on a Chemically Reacting Non-Newtonian Casson Fluid Over a Vertically Stretched Magnetized Surface

Heat Transfer on a Chemically Reacting Non-Newtonian Casson Fluid Over a Vertically Stretched Magnetized Surface

Journal of Nanofluids

An extensive investigation into heat transfer through Casson fluid on a stretched magnetized surf... more An extensive investigation into heat transfer through Casson fluid on a stretched magnetized surface with presence of chemical reactants has been conducted. The magnetic strength influence at the plate surface and within the body of the fluid has been analysed as well as effects of radiation and convection fields are considered. The methods of similarity analysis have been used to transform the multivariable dependent equations modelling the flow to a single variable dependent equation. The emerged dimensionless parameters describing the flow have been presented numerically. The effects of magnetization of the surface along with the bulk fluid are presented in tables and graphs. It is evident that magnetizing the surface enhances the temperature distribution near the surface. Similar results can be seen with the coefficient of wall resistance, and the mass and transfer rate on the magnitised plate. From the study, it is recommended that surface magnetization can influence flow kinem...

Research paper thumbnail of Rectification in Chiral Carbon Nanotubes with Hot Electron Injection

Rectification in Chiral Carbon Nanotubes with Hot Electron Injection

Journal of Experimental and Theoretical Physics, 2020

The novel effect of direct current generation by carbon nanotubes with hot electron injection whi... more The novel effect of direct current generation by carbon nanotubes with hot electron injection which may arise due to an electromagnetic radiation with commensurate frequencies has been theoretically investigated using the semiclassical Boltzmann kinetic equation with relaxation time assumed constant. The nonlinearity of the current voltage characteristics and the chiral effects have been considered. We note that the direct current is a result of the strong nonprabolicity of the energy of the carbon nanotubes for the case where it Bloch oscillates. It is shown that the novel expression for the direct current generation strongly and significantly dependence on the hot electron injection rate, which leads to strong oscillatory behavior and the shift of the regions of absolute negative conductivity from low to higher dimensionless amplitude β values with increasing injection rate. We predict that carbon nanotubes with hot electron injection may be useful for generation of direct current.

Research paper thumbnail of Magnetoplasmon Excitations at Graphene Vortex Hall Fluid Edge

Physics Research International, 2016

We investigate magnetoplasmon dynamics localized on the edges of graphene vortex Hall fluid. The ... more We investigate magnetoplasmon dynamics localized on the edges of graphene vortex Hall fluid. The vortex matter captures an anomalous term that causes vortex localization near fluid boundary and creates a double boundary layer,Δ0∝(β-1)lBwithβbeing filling factor. The term also has qualitative effect on resonant excitations of edge magnetoplasmons. We found that, for sharp edges under experimental conditions, graphene edge magnetoplasmon (EMP) resonances have similar behavior as in recent experiments. Gradual distinctions arise for smooth edges in the presence of the anomalous term, where a weak EMP peak appears. The second peak becomes well noticed as the smoothness is increased. We identified the resonant mode as an Inter-EMP. It originates from the oscillations of charges in the inner boundary of the double layer. The present observation brings to light the direct cause of Inter-EMP which remained to be detected in graphene experiments.

Research paper thumbnail of Effect of annealing temperatures on the self-assembly properties of iron (III) oxide nanoparticles

The use of Atomic Force Microscopy (AFM) to investigate the effect of different annealing tempera... more The use of Atomic Force Microscopy (AFM) to investigate the effect of different annealing temperatures on the self-assembly properties of Iron (III) oxide nanoparticles prepared by the Langmuir-Schaefer method is experimentally demonstrated and discussed. Ferritin molecules containing a self-assembled core of iron oxide undergo thermal treatment to produce the nanoparticles. When the Iron (III) oxide nanoparticles were subjected to annealing temperatures, they were found to coalesce especially at the boundary of the graphitic substrate to conserve energy. At higher temperatures the particles were again seen to coalesce more, forming islands at the graphitic boundary. Further studies revealed that these islands represented different phases of Iron (III) oxide nanoparticles that resembledγ-Fe 2 O 3 , α-Fe 2 O 3 and a third phase that likely was a combination of γ-Fe 2 O 3 and α-Fe 2 O 3 .

Research paper thumbnail of Hydrodynamic study of edge spin-vortex excitations of fractional quantum Hall fluid

Physics Letters A, 2016

We undertake a theoretical study of edge spin-vortex excitations in fractional quantum Hall fluid... more We undertake a theoretical study of edge spin-vortex excitations in fractional quantum Hall fluid. This is done in view of quantised Euler hydrodynamics theory. The dispersions of true excitations for fractions within 0 ≤ ν ≤ 1 are simulated which exhibit universal similarities and differences in behaviour. The differences arise from different edge smoothness and spin (pseudo-spin) polarisations, in addition to spincharge competition. In particular, tuning the spin-charge factor causes coherent spin flipping associated with partial and total polarisations of edge spin-vortices. This observation is tipped as an ideal mechanism for realisation of functional spintronic devices.

Research paper thumbnail of Photon-Assisted Process and High-Harmonic Dynamic Localization in Graphene Nanoribbons

arXiv (Cornell University), 2012

We used a complete tight-binding band structure of graphene nanoribbon to obtain, for the first t... more We used a complete tight-binding band structure of graphene nanoribbon to obtain, for the first time, analytical techniques for observing photon assisted transport, and dynamic localization of electrons in the graphene nanoribbons. When the ribbons are subject to a multi-frequency dc-ac field, photon assisted replicas show up at rather strong drive force. The strong dependence of the photon peaks on ac amplitudes allow for high-harmonic dynamic oscillations at these amplitudes. We identified regions of positive differential conductivity where a nanoelectronic graphene device may be operated as a small signal amplifier. Our research has also reveal another quantum mechanical phenomenon, fractional photon assisted transport, when the stark factor r>1r > 1r>1.

Research paper thumbnail of Effects of Temperature Fluctuations on Darcy-Forchheimer Flow of Oil-Based Nanofluid with Activation Energy and Velocity Slip

Earthline Journal of Mathematical Sciences

The effects of fluctuating temperature on Darcy-Forchheimer flow of oil-based nanofluid with acti... more The effects of fluctuating temperature on Darcy-Forchheimer flow of oil-based nanofluid with activation energy and velocity slip has been analyzed. Similarity transformation was used to transform the governing partial differential equations into coupled nonlinear ordinary differential equations and solved numerically with the aid of the fourth order Runge-Kutta algorithm with a shooting technique. Results for the embedded parameters controlling the flow dynamics have been tabulated and illustrated graphically. The slip velocity parameter was found to enhance the Nusselt number but depleted both the skin friction coefficient and Sherwood number while the local inertial was noted to increase both the skin friction coefficient and Sherwood number but diminishes the Nusselt number. These results indicate that the velocity slip parameter and local inertial coefficient can be used to control flow characteristics in industrial and engineering systems.

Research paper thumbnail of On MHD Flow of Non-newtonian Viscoelastic Fluid over a Stretched Magnetized Surface

On MHD Flow of Non-newtonian Viscoelastic Fluid over a Stretched Magnetized Surface

American Journal of Applied Mathematics

Research paper thumbnail of Appearance of Large Amplitude Current Dynamics as a Result of Bragg Reflection in Carbon Nanotubes

arXiv (Cornell University), Jul 12, 2012

We report on theoretical analysis of large amplitude current dynamics due to Bragg reflections in... more We report on theoretical analysis of large amplitude current dynamics due to Bragg reflections in carbon nanotubes exposed to an external electric field. Using the kinetic equation with constant relaxation time, an analytical expression for the current density is obtained. Our results suggest that Bloch gain exists up to frequencies on the order of the Bloch frequency. We noted that due to the high density of states of conduction electrons in metallic carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency gain than the corresponding values for semiconducting ones. We suggest that this phenomenon can be used for domainless multiplication of the frequency of an electromagnetic signal at room temperature.

Research paper thumbnail of Impact of Thermophoretic Transport of Al2O3 Nanoparticles on Viscoelastic Flow of Oil-Based Nanofluid over a Porous Exponentially Stretching Surface with Activation Energy

Engineering Transactions, 2019

The influence of thermophoretic transport of Al2O3 nanoparticles on heat and mass transfer in vis... more The influence of thermophoretic transport of Al2O3 nanoparticles on heat and mass transfer in viscoelastic flow of oil-based nanofluid past porous exponentially stretching surface with activation energy has been examined. Similarity technique was employed to transform the governing partial differential equations into a coupled fourth-order ordinary differential equations which were reduced to a system of first-order ordinary differential equations and then solved numerically using the fourth-order Runge-Kutta algorithm with a shooting method. The results for various controlling parameters were tabulated and graphically illustrated. It was found that the thermophoretic transport of Al2O3 nanoparticles did not affect the rate of flow and heat transfer at the surface but it affected the rate of mass transfer of the nanofluid which decayed the solutal boundary layer thickness. This study also revealed that activation energy retards the rate of mass transfer which causes a thickening of ...

Research paper thumbnail of Behaviour of hot electrons under the dc field in chiral carbon nanotubes

arXiv: Mesoscale and Nanoscale Physics, 2016

Behaviour of hot electrons under the influence of dc field in carbon nanotubes is theoretically c... more Behaviour of hot electrons under the influence of dc field in carbon nanotubes is theoretically considered. The study was done semi-classically by solving Boltzmann transport equation with the presence of the hot electrons source to derive the current densities. Plots of the normalized axial current density versus electric field strength of the chiral CNTs reveal a negative differential conductivity (NDC). Unlike achiral CNTs, the NDC occurs at a low field about mathrm6kV/cm\mathrm{6\ kV/cm}mathrm6kV/cm for chiral CNT. We further observed that the switch from NDC to PDC occurs at lower dc field in chiral CNTs than achiral counterparts. Hence the suppression of the unwanted domain instability usually associated with NDC and a potential generation of terahertz radiations occurs at low electric field for chiral CNTs.

Research paper thumbnail of Radius dependence of the electrical conductivity of zigzgag carbon nanotubes

Radius dependence of the electrical conductivity of zigzgag carbon nanotubes

Physica E: Low-dimensional Systems and Nanostructures, 2021

Abstract The radius dependence of the electrical conductivity of metallic and semiconducting zigz... more Abstract The radius dependence of the electrical conductivity of metallic and semiconducting zigzag carbon nanotubes (CNTs) is theoretically studied. The investigation was done semiclassically by solving the Boltzmann transport equation to derive current density as a function of a homogenous axial dc field and radius of the tube. The analysis was numerically carried out by varying the radius of the materials at a constant temperature. Plots of the normalized current density versus dc field applied along the axis of both materials are presented. We observed that in the case of the metallic zigzag CNTs as the radius increases, the electrical conductivity decreases. On the other hand, in the semiconducting zigzag CNT there was an increase as radius increases. This research shows that thinner metallic zigzag CNTs and thicker semiconducting zigzag CNTs are better conductors of electricity. This investigation therefore offers way of obtaining higher electrical conductivity in both materials without doping. This study therefore shows applications in the development of current conducting nano-devices for scientific systems.

Research paper thumbnail of On the Flow of Oil-Based Nanofluid on a Stretching Permeable Surface with Radiative Heat Transfer and Dissipative Energy

On the Flow of Oil-Based Nanofluid on a Stretching Permeable Surface with Radiative Heat Transfer and Dissipative Energy

Defect and Diffusion Forum, 2021

Heat transport processes through radiation in a dissipative flow of Al2O3 and CuO oil-based nanof... more Heat transport processes through radiation in a dissipative flow of Al2O3 and CuO oil-based nanofluids has been discussed. The equations modeling the flow has been transformed using similarity variables into coupled nonlinear higher order ordinary differential equations. These equations are solved by employing the fourth order Runge-Kutta algorithm and a shooting technique. The results for the embedded parameters were tabulated and depicted graphically. The study revealed that oil-based nanofluid of CuO has a better rate of heat transfer than Al2O3 oil-based nanofluid with increased radiation. Thus, the study concluded that CuO oil-based nanofluid has a superior heat transfer characteristic and thus preferred for radiation hardening.

Research paper thumbnail of Heat Transfer in a Magnetohydrodynamic Boundary Layer Flow of a Non-Newtonian Casson Fluid Over an Exponentially Stretching Magnetized Surface

Journal of Nanofluids, 2021

In this current paper, an investigation has been conducted on the magnetohydrodynamic boundary la... more In this current paper, an investigation has been conducted on the magnetohydrodynamic boundary layer flow of non-Newtonian Casson fluids on magnetized sheet with an exponentially stretching sheet. The similarity approach has been used to transform the governing models for Casson fluid to ordinary differential equations. We presented numerical results for momentum, energy and concentration equation parameters. Effects of the magnetized sheet and varying all the emerged parameters on the flow of Casson fluid with respect to the friction between the fluid and the surface, temperature and concentration are presented in tables. As a result of the induced magnetization of the sheet, the thickness of the thermal boundary layer has been enhanced. This behaviour brings a considerable reduction to the heat transfer. The induced magnetized sheet has a similar influence on the skin friction, Nusselt number and the Sherwood number. We however proposed incorporation of magnetized surfaces in MHD ...

Research paper thumbnail of Hydrodynamics of vortex memory system driven by edge-current and boundary magnetization

arXiv (Cornell University), May 5, 2024

In this study, a magnetohydrodynamic model is developed to study the dynamics of vortices driven ... more In this study, a magnetohydrodynamic model is developed to study the dynamics of vortices driven by edge-current. Two modeled equations for fluid and magnetic field variables are each transformed into diffusion equation for vorticity and poisson equation for stream function. A numerical solution method is designed using a simplified Lattice Boltzmann method (LBM). The LBM-D2Q5 scheme is utilized to obtain the numerical solutions for the fluid and magnetic field variables. Understanding the hydrodynamic behavior of systems employed in vortex-based memory systems is crucial for reliability and performance optimization. Based on this motivation, the effect of applied edge-current on the hydrodynamic and magnetic vortex configurations are analyzed through numerical simulations. The impact of the boundary magnetization is also conducted, by varying the strength of the magnetic field at the bottom boundary. The obtained graphical results provide some insights into the design and operation of vortex-based memory systems for next-generation data storage applications.

Research paper thumbnail of MHD flow of blood-based hybrid nanofluid through a stenosed artery with thermal radiation effect

MHD flow of blood-based hybrid nanofluid through a stenosed artery with thermal radiation effect

Case studies in thermal engineering, Apr 1, 2024

Research paper thumbnail of Stark-cyclotron resonance in an array of carbon nanotubes

arXiv (Cornell University), Jun 1, 2015

Using the kinetic approach based on the semiclassical Boltzmanns transport equation with constant... more Using the kinetic approach based on the semiclassical Boltzmanns transport equation with constant relaxation time, we theoretically studied the Starkcyclotron resonance in an array of carbon nanotubes. Exact expression for the current density was obtained. We noted that Stark-cyclotron resonance occurs when the Larmor frequency coincides with the Stark frequency.

Research paper thumbnail of Nonlinear Conductivity in Graphene

arXiv (Cornell University), Oct 23, 2015

We consider the tight-binding approximation for the description of energy bands of graphene, toge... more We consider the tight-binding approximation for the description of energy bands of graphene, together with the standard Boltzmanns transport equation and constant relaxation time, an expression for the conductivity was obtained. We predicted strong nonlinear effects in graphene which may be useful for high frequency generation.

Research paper thumbnail of Influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes under homogeneous axial dc field

Influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes under homogeneous axial dc field

Low Temperature Physics

We present theoretical framework investigations of the influence of temperature variation on the ... more We present theoretical framework investigations of the influence of temperature variation on the electrical conductivity of zigzag carbon nanotubes (CNTs) under the applied homogeneous axial dc field. This study was done semiclassically by solving Boltzmann transport equation to derive the current density of zigzag CNT as a function of homogenous axial dc field and temperature. Plots of the normalized current density versus homogeneous dc field applied along the axis of semiconducting zigzag CNTs as room temperature increases from 293 to 299 K revealed a significant increase in electrical conductivity, whereas in metallic zigzag CNTs, almost constant or a negligible decrease in electrical conductivity is observed. The study predicts semiconducting zigzag CNT as a potential material for temperature sensors since it exhibits a faster response and a substantially higher sensitivity to room temperature changes than the metallic counterpart. The electrical conductivity of metallic zigzag...

Research paper thumbnail of Enhanced nonlinear conductivity due to hot-electron injection in carbon nanotubes

Enhanced nonlinear conductivity due to hot-electron injection in carbon nanotubes

Low Temperature Physics

We have theoretically obtained an expression for the current density in a terahertz field due to ... more We have theoretically obtained an expression for the current density in a terahertz field due to hot-electron injection in carbon nanotubes. The injection modifies the stationary distribution function and leads to a qualitative change in the behavior of the current-voltage characteristics and causes absolute negative conductivity. We compared the current-voltage characteristic behavior at different injection rates and observed a drastic change in the current density and absolute negative conductivity values. We propose that carbon nanotubes with hot-electron injection may be useful for high-frequency applications.

Research paper thumbnail of Heat Transfer on a Chemically Reacting Non-Newtonian Casson Fluid Over a Vertically Stretched Magnetized Surface

Heat Transfer on a Chemically Reacting Non-Newtonian Casson Fluid Over a Vertically Stretched Magnetized Surface

Journal of Nanofluids

An extensive investigation into heat transfer through Casson fluid on a stretched magnetized surf... more An extensive investigation into heat transfer through Casson fluid on a stretched magnetized surface with presence of chemical reactants has been conducted. The magnetic strength influence at the plate surface and within the body of the fluid has been analysed as well as effects of radiation and convection fields are considered. The methods of similarity analysis have been used to transform the multivariable dependent equations modelling the flow to a single variable dependent equation. The emerged dimensionless parameters describing the flow have been presented numerically. The effects of magnetization of the surface along with the bulk fluid are presented in tables and graphs. It is evident that magnetizing the surface enhances the temperature distribution near the surface. Similar results can be seen with the coefficient of wall resistance, and the mass and transfer rate on the magnitised plate. From the study, it is recommended that surface magnetization can influence flow kinem...

Research paper thumbnail of Rectification in Chiral Carbon Nanotubes with Hot Electron Injection

Rectification in Chiral Carbon Nanotubes with Hot Electron Injection

Journal of Experimental and Theoretical Physics, 2020

The novel effect of direct current generation by carbon nanotubes with hot electron injection whi... more The novel effect of direct current generation by carbon nanotubes with hot electron injection which may arise due to an electromagnetic radiation with commensurate frequencies has been theoretically investigated using the semiclassical Boltzmann kinetic equation with relaxation time assumed constant. The nonlinearity of the current voltage characteristics and the chiral effects have been considered. We note that the direct current is a result of the strong nonprabolicity of the energy of the carbon nanotubes for the case where it Bloch oscillates. It is shown that the novel expression for the direct current generation strongly and significantly dependence on the hot electron injection rate, which leads to strong oscillatory behavior and the shift of the regions of absolute negative conductivity from low to higher dimensionless amplitude β values with increasing injection rate. We predict that carbon nanotubes with hot electron injection may be useful for generation of direct current.

Research paper thumbnail of Magnetoplasmon Excitations at Graphene Vortex Hall Fluid Edge

Physics Research International, 2016

We investigate magnetoplasmon dynamics localized on the edges of graphene vortex Hall fluid. The ... more We investigate magnetoplasmon dynamics localized on the edges of graphene vortex Hall fluid. The vortex matter captures an anomalous term that causes vortex localization near fluid boundary and creates a double boundary layer,Δ0∝(β-1)lBwithβbeing filling factor. The term also has qualitative effect on resonant excitations of edge magnetoplasmons. We found that, for sharp edges under experimental conditions, graphene edge magnetoplasmon (EMP) resonances have similar behavior as in recent experiments. Gradual distinctions arise for smooth edges in the presence of the anomalous term, where a weak EMP peak appears. The second peak becomes well noticed as the smoothness is increased. We identified the resonant mode as an Inter-EMP. It originates from the oscillations of charges in the inner boundary of the double layer. The present observation brings to light the direct cause of Inter-EMP which remained to be detected in graphene experiments.

Research paper thumbnail of Effect of annealing temperatures on the self-assembly properties of iron (III) oxide nanoparticles

The use of Atomic Force Microscopy (AFM) to investigate the effect of different annealing tempera... more The use of Atomic Force Microscopy (AFM) to investigate the effect of different annealing temperatures on the self-assembly properties of Iron (III) oxide nanoparticles prepared by the Langmuir-Schaefer method is experimentally demonstrated and discussed. Ferritin molecules containing a self-assembled core of iron oxide undergo thermal treatment to produce the nanoparticles. When the Iron (III) oxide nanoparticles were subjected to annealing temperatures, they were found to coalesce especially at the boundary of the graphitic substrate to conserve energy. At higher temperatures the particles were again seen to coalesce more, forming islands at the graphitic boundary. Further studies revealed that these islands represented different phases of Iron (III) oxide nanoparticles that resembledγ-Fe 2 O 3 , α-Fe 2 O 3 and a third phase that likely was a combination of γ-Fe 2 O 3 and α-Fe 2 O 3 .

Research paper thumbnail of Hydrodynamic study of edge spin-vortex excitations of fractional quantum Hall fluid

Physics Letters A, 2016

We undertake a theoretical study of edge spin-vortex excitations in fractional quantum Hall fluid... more We undertake a theoretical study of edge spin-vortex excitations in fractional quantum Hall fluid. This is done in view of quantised Euler hydrodynamics theory. The dispersions of true excitations for fractions within 0 ≤ ν ≤ 1 are simulated which exhibit universal similarities and differences in behaviour. The differences arise from different edge smoothness and spin (pseudo-spin) polarisations, in addition to spincharge competition. In particular, tuning the spin-charge factor causes coherent spin flipping associated with partial and total polarisations of edge spin-vortices. This observation is tipped as an ideal mechanism for realisation of functional spintronic devices.

Research paper thumbnail of Photon-Assisted Process and High-Harmonic Dynamic Localization in Graphene Nanoribbons

arXiv (Cornell University), 2012

We used a complete tight-binding band structure of graphene nanoribbon to obtain, for the first t... more We used a complete tight-binding band structure of graphene nanoribbon to obtain, for the first time, analytical techniques for observing photon assisted transport, and dynamic localization of electrons in the graphene nanoribbons. When the ribbons are subject to a multi-frequency dc-ac field, photon assisted replicas show up at rather strong drive force. The strong dependence of the photon peaks on ac amplitudes allow for high-harmonic dynamic oscillations at these amplitudes. We identified regions of positive differential conductivity where a nanoelectronic graphene device may be operated as a small signal amplifier. Our research has also reveal another quantum mechanical phenomenon, fractional photon assisted transport, when the stark factor r>1r > 1r>1.

Research paper thumbnail of Effects of Temperature Fluctuations on Darcy-Forchheimer Flow of Oil-Based Nanofluid with Activation Energy and Velocity Slip

Earthline Journal of Mathematical Sciences

The effects of fluctuating temperature on Darcy-Forchheimer flow of oil-based nanofluid with acti... more The effects of fluctuating temperature on Darcy-Forchheimer flow of oil-based nanofluid with activation energy and velocity slip has been analyzed. Similarity transformation was used to transform the governing partial differential equations into coupled nonlinear ordinary differential equations and solved numerically with the aid of the fourth order Runge-Kutta algorithm with a shooting technique. Results for the embedded parameters controlling the flow dynamics have been tabulated and illustrated graphically. The slip velocity parameter was found to enhance the Nusselt number but depleted both the skin friction coefficient and Sherwood number while the local inertial was noted to increase both the skin friction coefficient and Sherwood number but diminishes the Nusselt number. These results indicate that the velocity slip parameter and local inertial coefficient can be used to control flow characteristics in industrial and engineering systems.

Research paper thumbnail of On MHD Flow of Non-newtonian Viscoelastic Fluid over a Stretched Magnetized Surface

On MHD Flow of Non-newtonian Viscoelastic Fluid over a Stretched Magnetized Surface

American Journal of Applied Mathematics

Research paper thumbnail of Appearance of Large Amplitude Current Dynamics as a Result of Bragg Reflection in Carbon Nanotubes

arXiv (Cornell University), Jul 12, 2012

We report on theoretical analysis of large amplitude current dynamics due to Bragg reflections in... more We report on theoretical analysis of large amplitude current dynamics due to Bragg reflections in carbon nanotubes exposed to an external electric field. Using the kinetic equation with constant relaxation time, an analytical expression for the current density is obtained. Our results suggest that Bloch gain exists up to frequencies on the order of the Bloch frequency. We noted that due to the high density of states of conduction electrons in metallic carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency gain than the corresponding values for semiconducting ones. We suggest that this phenomenon can be used for domainless multiplication of the frequency of an electromagnetic signal at room temperature.

Research paper thumbnail of Impact of Thermophoretic Transport of Al2O3 Nanoparticles on Viscoelastic Flow of Oil-Based Nanofluid over a Porous Exponentially Stretching Surface with Activation Energy

Engineering Transactions, 2019

The influence of thermophoretic transport of Al2O3 nanoparticles on heat and mass transfer in vis... more The influence of thermophoretic transport of Al2O3 nanoparticles on heat and mass transfer in viscoelastic flow of oil-based nanofluid past porous exponentially stretching surface with activation energy has been examined. Similarity technique was employed to transform the governing partial differential equations into a coupled fourth-order ordinary differential equations which were reduced to a system of first-order ordinary differential equations and then solved numerically using the fourth-order Runge-Kutta algorithm with a shooting method. The results for various controlling parameters were tabulated and graphically illustrated. It was found that the thermophoretic transport of Al2O3 nanoparticles did not affect the rate of flow and heat transfer at the surface but it affected the rate of mass transfer of the nanofluid which decayed the solutal boundary layer thickness. This study also revealed that activation energy retards the rate of mass transfer which causes a thickening of ...

Research paper thumbnail of Behaviour of hot electrons under the dc field in chiral carbon nanotubes

arXiv: Mesoscale and Nanoscale Physics, 2016

Behaviour of hot electrons under the influence of dc field in carbon nanotubes is theoretically c... more Behaviour of hot electrons under the influence of dc field in carbon nanotubes is theoretically considered. The study was done semi-classically by solving Boltzmann transport equation with the presence of the hot electrons source to derive the current densities. Plots of the normalized axial current density versus electric field strength of the chiral CNTs reveal a negative differential conductivity (NDC). Unlike achiral CNTs, the NDC occurs at a low field about mathrm6kV/cm\mathrm{6\ kV/cm}mathrm6kV/cm for chiral CNT. We further observed that the switch from NDC to PDC occurs at lower dc field in chiral CNTs than achiral counterparts. Hence the suppression of the unwanted domain instability usually associated with NDC and a potential generation of terahertz radiations occurs at low electric field for chiral CNTs.

Research paper thumbnail of Radius dependence of the electrical conductivity of zigzgag carbon nanotubes

Radius dependence of the electrical conductivity of zigzgag carbon nanotubes

Physica E: Low-dimensional Systems and Nanostructures, 2021

Abstract The radius dependence of the electrical conductivity of metallic and semiconducting zigz... more Abstract The radius dependence of the electrical conductivity of metallic and semiconducting zigzag carbon nanotubes (CNTs) is theoretically studied. The investigation was done semiclassically by solving the Boltzmann transport equation to derive current density as a function of a homogenous axial dc field and radius of the tube. The analysis was numerically carried out by varying the radius of the materials at a constant temperature. Plots of the normalized current density versus dc field applied along the axis of both materials are presented. We observed that in the case of the metallic zigzag CNTs as the radius increases, the electrical conductivity decreases. On the other hand, in the semiconducting zigzag CNT there was an increase as radius increases. This research shows that thinner metallic zigzag CNTs and thicker semiconducting zigzag CNTs are better conductors of electricity. This investigation therefore offers way of obtaining higher electrical conductivity in both materials without doping. This study therefore shows applications in the development of current conducting nano-devices for scientific systems.

Research paper thumbnail of On the Flow of Oil-Based Nanofluid on a Stretching Permeable Surface with Radiative Heat Transfer and Dissipative Energy

On the Flow of Oil-Based Nanofluid on a Stretching Permeable Surface with Radiative Heat Transfer and Dissipative Energy

Defect and Diffusion Forum, 2021

Heat transport processes through radiation in a dissipative flow of Al2O3 and CuO oil-based nanof... more Heat transport processes through radiation in a dissipative flow of Al2O3 and CuO oil-based nanofluids has been discussed. The equations modeling the flow has been transformed using similarity variables into coupled nonlinear higher order ordinary differential equations. These equations are solved by employing the fourth order Runge-Kutta algorithm and a shooting technique. The results for the embedded parameters were tabulated and depicted graphically. The study revealed that oil-based nanofluid of CuO has a better rate of heat transfer than Al2O3 oil-based nanofluid with increased radiation. Thus, the study concluded that CuO oil-based nanofluid has a superior heat transfer characteristic and thus preferred for radiation hardening.

Research paper thumbnail of Heat Transfer in a Magnetohydrodynamic Boundary Layer Flow of a Non-Newtonian Casson Fluid Over an Exponentially Stretching Magnetized Surface

Journal of Nanofluids, 2021

In this current paper, an investigation has been conducted on the magnetohydrodynamic boundary la... more In this current paper, an investigation has been conducted on the magnetohydrodynamic boundary layer flow of non-Newtonian Casson fluids on magnetized sheet with an exponentially stretching sheet. The similarity approach has been used to transform the governing models for Casson fluid to ordinary differential equations. We presented numerical results for momentum, energy and concentration equation parameters. Effects of the magnetized sheet and varying all the emerged parameters on the flow of Casson fluid with respect to the friction between the fluid and the surface, temperature and concentration are presented in tables. As a result of the induced magnetization of the sheet, the thickness of the thermal boundary layer has been enhanced. This behaviour brings a considerable reduction to the heat transfer. The induced magnetized sheet has a similar influence on the skin friction, Nusselt number and the Sherwood number. We however proposed incorporation of magnetized surfaces in MHD ...