Ce modele decrit la reponse du segment de dislocation ancre a la contrainte alternative appliquee... more Ce modele decrit la reponse du segment de dislocation ancre a la contrainte alternative appliquee. Ce modele explique rigoureusement l'origine du premier des deux pics de relaxation observe a 150°C
Volume 1 PROGRESS IN PHYSICS January, 2011 Photon-Assisted Resonant Chiral Tunneling Through a Bi... more Volume 1 PROGRESS IN PHYSICS January, 2011 Photon-Assisted Resonant Chiral Tunneling Through a Bilayer Graphene Barrier Aziz N. Mina∗ and Adel H. Phillips ∗ Faculty of Science, Beni-Suef University, Beni-Suef, Egypt Faculty of Engineering, Ain-Shams ...
Journal of Computational and Theoretical Nanoscience, Apr 1, 2014
Strain sensing via quantum nanodevice is investigated in the present paper under the effect of an... more Strain sensing via quantum nanodevice is investigated in the present paper under the effect of an ac-field. This nanodevice is modeled as semiconducting carbon nanotube (CNT) quantum dot. This CNT quantum dot is connected to two metallic leads. A metallic gate is used to govern the electrostatics and the switching of the CNT channel. A back gate is used to
The stellar energy loss rate due to the production of neutrino pairs by Bremsstrahlung is calcula... more The stellar energy loss rate due to the production of neutrino pairs by Bremsstrahlung is calculated for neutron stars in the presence of a strong magnetic field (B ⩽ 1012 G) and the Coulomb field of the positive ions. The calculated energy loss rates are applied to nonrelativistic electrons at low densities ⩽ 105 gm/cm3 and relatively low temperatures T ⩽ 109 K. Neutrino-Paar-Bremsstrahlung aus einem heisen Plasma in Gegenwart eines starken Magnetfeldes Es wird der Energie-Verlust durch die Erzeugung von Neutrino-Paaren durch Bremsstrahlung in der Materie der Neutronensterne in Gegenwart eines starken Magnetfeldes (B ⩽ 1012 G) und des Coulomb-Feldes der positiven Ionen berechnet. Die erhaltenen Ergebnisse werden auf nichtrelativistische Elektronen bei niedrigen Dichten ⩽ 105 gm/cm3 und relativ niedrigen Temperaturen T ⩽ 109 K angewendet.
Modelling and Simulation in Materials Science and Engineering, Jul 1, 1993
ABSTRACT The authors considered the attenuation coefficient due to the two systems of heat phonon... more ABSTRACT The authors considered the attenuation coefficient due to the two systems of heat phonons which have been detected by ultrasonic attenuation experiments. Using model parameters characterizing metals (Zn, Al, Fe) under test, the authors calculated the temperature variation of the attenuation coefficient for Zn, Al, and Fe . Despite the complicated attenuation spectrum, the agreement between theoretical and experimental results was found to be quite satisfactory.
ABSTRACT Thermal shot noise, thermal voltage and thermo power are studied through a carbon nanotu... more ABSTRACT Thermal shot noise, thermal voltage and thermo power are studied through a carbon nanotube quantum dot coupled to two leads with random roughness of amplitude on each of the two boundaries, under the effect of microwave field, and magnetic field. The expressions for the thermal shot noise and thermal energy are deduced when the barrier strength and contact area are taken into consideration. A model for such mesoscopic devices is proposed as a carbon nanotube quantum dot coupled to two leads with random roughness of amplitude on each of the two boundaries. The results show oscillatory behaviors of the dependence of the thermal shot noise on the studied parameters. The thermopower oscillates with the variation of the contact area, and the peak heights decrease linearly with the contact area and increases with temperature. This trend of behavior is due to the interplay of the induced microwave photons and the tunneling rate through the side bands. This research is important for using a model as a high-frequency shot noise detector and the thermopower is sensitive to the energy dependence of the conductance.
ABSTRACT We investigate the thermodynamics properties of mesoscopic quantum nanowire devices, suc... more ABSTRACT We investigate the thermodynamics properties of mesoscopic quantum nanowire devices, such as the effect of electron-phonon relaxation time, Peltier coefficient, carrier concentration, frequency of this field, and channel width. The influence of time-varying fields on the transport through such device has been taken into consideration. This device is modelled as nanowires connecting to two reservoirs. The two-dimensional electron gas in a GaAs–AlGaAs heterojunction has a Fermi wave length which is a hundred times larger than that in a metal. The results show the oscillatory behaviour of dependence of the thermo power on frequency of the induced field. These results agree with the existing experiments and may be important for electronic nanodevices.
A spin dependent Peltier effect in graphene nanodevice is investigated. This nanodevice is modele... more A spin dependent Peltier effect in graphene nanodevice is investigated. This nanodevice is modeled as ferromagnetic graphene/ superconducting graphene junction with Schottky barrier of delta-type at the interface of the junction. The Peltier coefficient is expressed in terms of spin-dependent Andreev reflection and normal reflection which will be deduced by solving Dirac-Bogoliubov-deGennes equation in one dimension. Numerical calculations are performed for two different superconducting layers under the effects of the induced ac-field and magnetic field. Results show that the present nanodevice operates only in narrow band of THz frequencies. Also, the present results might indicate that the present nanodevice is stable under the effect of magnetic field, which must be needed for quantum information processing. The present graphene nanodevice based on Peltier effect might be used as coolers for nanoelectronic devices such as nanocontrollers and computer CPUs. The present research is very important in the field of spin caloritronics on the nanoscale systems and at low temperatures.
The spin dependent conductance of graphene field effect transistor is investigated in the present... more The spin dependent conductance of graphene field effect transistor is investigated in the present paper. Graphene field effect transistor is modeled as: ferromagnetic grapheme / superconducting graphene junction with Schottky barrier of -type at the interface of the junction. The conductance is deduced by using Landuar-Buttiker equation and the corresponding spin dependent Andreev reflection and the normal reflection coefficients are deduced by solving Dirac-Bogoliubov-deGennes equation in one dimension. The spin polarization transport is conducted under the effect of photon of an induced ac-field and magnetic field. Numerical calculations are performed for conductance for both parallel and antiparallel spin alignments and the corresponding spin polarization and giant magnetoresistance are also calculated. In our calculations we consider two different superconducting layers. Results show that the spin-dependent specular Andreev reflection in the present studied junction plays an important role for designing such nanodevice. Also, the Schottky barrier between the ferromagnetic graphene and superconductor graphene regions might be responsible for the conductance dip for both parallel and antiparallel spin alignments. The present paper is very important for spin filter, superconducting qubits needed for quantum information processing at low temperatures and also it might be used as THz oscillator.
The use of single walled carbon nanotube-based nanoelectromechanical system (NEMS) resonator to s... more The use of single walled carbon nanotube-based nanoelectromechanical system (NEMS) resonator to sense the biomolecules’ mass is investigated under the influence of an external ac-field. A single walled carbon nanotube (SWCNT) cantilever has been proposed and studied if the mass is attached at the tip or various intermediate positions. The shift of the resonant frequency and the quality factor have been investigated and show high sensitivity to the attached mass of biomolecule and its position. The proposed SWCNT-based NEMS resonator is a good candidate for sensing and tracing biomolecules’ mass as concentration of acetone in human exhale, resulting in a painless, correct, and simple diabetics’ diagnosis.
Ce modele decrit la reponse du segment de dislocation ancre a la contrainte alternative appliquee... more Ce modele decrit la reponse du segment de dislocation ancre a la contrainte alternative appliquee. Ce modele explique rigoureusement l'origine du premier des deux pics de relaxation observe a 150°C
Volume 1 PROGRESS IN PHYSICS January, 2011 Photon-Assisted Resonant Chiral Tunneling Through a Bi... more Volume 1 PROGRESS IN PHYSICS January, 2011 Photon-Assisted Resonant Chiral Tunneling Through a Bilayer Graphene Barrier Aziz N. Mina∗ and Adel H. Phillips ∗ Faculty of Science, Beni-Suef University, Beni-Suef, Egypt Faculty of Engineering, Ain-Shams ...
Journal of Computational and Theoretical Nanoscience, Apr 1, 2014
Strain sensing via quantum nanodevice is investigated in the present paper under the effect of an... more Strain sensing via quantum nanodevice is investigated in the present paper under the effect of an ac-field. This nanodevice is modeled as semiconducting carbon nanotube (CNT) quantum dot. This CNT quantum dot is connected to two metallic leads. A metallic gate is used to govern the electrostatics and the switching of the CNT channel. A back gate is used to
The stellar energy loss rate due to the production of neutrino pairs by Bremsstrahlung is calcula... more The stellar energy loss rate due to the production of neutrino pairs by Bremsstrahlung is calculated for neutron stars in the presence of a strong magnetic field (B ⩽ 1012 G) and the Coulomb field of the positive ions. The calculated energy loss rates are applied to nonrelativistic electrons at low densities ⩽ 105 gm/cm3 and relatively low temperatures T ⩽ 109 K. Neutrino-Paar-Bremsstrahlung aus einem heisen Plasma in Gegenwart eines starken Magnetfeldes Es wird der Energie-Verlust durch die Erzeugung von Neutrino-Paaren durch Bremsstrahlung in der Materie der Neutronensterne in Gegenwart eines starken Magnetfeldes (B ⩽ 1012 G) und des Coulomb-Feldes der positiven Ionen berechnet. Die erhaltenen Ergebnisse werden auf nichtrelativistische Elektronen bei niedrigen Dichten ⩽ 105 gm/cm3 und relativ niedrigen Temperaturen T ⩽ 109 K angewendet.
Modelling and Simulation in Materials Science and Engineering, Jul 1, 1993
ABSTRACT The authors considered the attenuation coefficient due to the two systems of heat phonon... more ABSTRACT The authors considered the attenuation coefficient due to the two systems of heat phonons which have been detected by ultrasonic attenuation experiments. Using model parameters characterizing metals (Zn, Al, Fe) under test, the authors calculated the temperature variation of the attenuation coefficient for Zn, Al, and Fe . Despite the complicated attenuation spectrum, the agreement between theoretical and experimental results was found to be quite satisfactory.
ABSTRACT Thermal shot noise, thermal voltage and thermo power are studied through a carbon nanotu... more ABSTRACT Thermal shot noise, thermal voltage and thermo power are studied through a carbon nanotube quantum dot coupled to two leads with random roughness of amplitude on each of the two boundaries, under the effect of microwave field, and magnetic field. The expressions for the thermal shot noise and thermal energy are deduced when the barrier strength and contact area are taken into consideration. A model for such mesoscopic devices is proposed as a carbon nanotube quantum dot coupled to two leads with random roughness of amplitude on each of the two boundaries. The results show oscillatory behaviors of the dependence of the thermal shot noise on the studied parameters. The thermopower oscillates with the variation of the contact area, and the peak heights decrease linearly with the contact area and increases with temperature. This trend of behavior is due to the interplay of the induced microwave photons and the tunneling rate through the side bands. This research is important for using a model as a high-frequency shot noise detector and the thermopower is sensitive to the energy dependence of the conductance.
ABSTRACT We investigate the thermodynamics properties of mesoscopic quantum nanowire devices, suc... more ABSTRACT We investigate the thermodynamics properties of mesoscopic quantum nanowire devices, such as the effect of electron-phonon relaxation time, Peltier coefficient, carrier concentration, frequency of this field, and channel width. The influence of time-varying fields on the transport through such device has been taken into consideration. This device is modelled as nanowires connecting to two reservoirs. The two-dimensional electron gas in a GaAs–AlGaAs heterojunction has a Fermi wave length which is a hundred times larger than that in a metal. The results show the oscillatory behaviour of dependence of the thermo power on frequency of the induced field. These results agree with the existing experiments and may be important for electronic nanodevices.
A spin dependent Peltier effect in graphene nanodevice is investigated. This nanodevice is modele... more A spin dependent Peltier effect in graphene nanodevice is investigated. This nanodevice is modeled as ferromagnetic graphene/ superconducting graphene junction with Schottky barrier of delta-type at the interface of the junction. The Peltier coefficient is expressed in terms of spin-dependent Andreev reflection and normal reflection which will be deduced by solving Dirac-Bogoliubov-deGennes equation in one dimension. Numerical calculations are performed for two different superconducting layers under the effects of the induced ac-field and magnetic field. Results show that the present nanodevice operates only in narrow band of THz frequencies. Also, the present results might indicate that the present nanodevice is stable under the effect of magnetic field, which must be needed for quantum information processing. The present graphene nanodevice based on Peltier effect might be used as coolers for nanoelectronic devices such as nanocontrollers and computer CPUs. The present research is very important in the field of spin caloritronics on the nanoscale systems and at low temperatures.
The spin dependent conductance of graphene field effect transistor is investigated in the present... more The spin dependent conductance of graphene field effect transistor is investigated in the present paper. Graphene field effect transistor is modeled as: ferromagnetic grapheme / superconducting graphene junction with Schottky barrier of -type at the interface of the junction. The conductance is deduced by using Landuar-Buttiker equation and the corresponding spin dependent Andreev reflection and the normal reflection coefficients are deduced by solving Dirac-Bogoliubov-deGennes equation in one dimension. The spin polarization transport is conducted under the effect of photon of an induced ac-field and magnetic field. Numerical calculations are performed for conductance for both parallel and antiparallel spin alignments and the corresponding spin polarization and giant magnetoresistance are also calculated. In our calculations we consider two different superconducting layers. Results show that the spin-dependent specular Andreev reflection in the present studied junction plays an important role for designing such nanodevice. Also, the Schottky barrier between the ferromagnetic graphene and superconductor graphene regions might be responsible for the conductance dip for both parallel and antiparallel spin alignments. The present paper is very important for spin filter, superconducting qubits needed for quantum information processing at low temperatures and also it might be used as THz oscillator.
The use of single walled carbon nanotube-based nanoelectromechanical system (NEMS) resonator to s... more The use of single walled carbon nanotube-based nanoelectromechanical system (NEMS) resonator to sense the biomolecules’ mass is investigated under the influence of an external ac-field. A single walled carbon nanotube (SWCNT) cantilever has been proposed and studied if the mass is attached at the tip or various intermediate positions. The shift of the resonant frequency and the quality factor have been investigated and show high sensitivity to the attached mass of biomolecule and its position. The proposed SWCNT-based NEMS resonator is a good candidate for sensing and tracing biomolecules’ mass as concentration of acetone in human exhale, resulting in a painless, correct, and simple diabetics’ diagnosis.
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