scholarly journals Magnetocaloric Effect in Non-Interactive Electron Systems: “The Landau Problem” and Its Extension to Quantum Dots

Entropy ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 557 ◽  
Author(s):  
Oscar Negrete ◽  
Francisco Peña ◽  
Juan Florez ◽  
Patricio Vargas
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Magnetocaloric Effect ◽  
Cyclotron Frequency ◽  
The Other ◽  
Electron Systems ◽  
Optimal Region ◽  
Potential Trap ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential

In this work, we report the magnetocaloric effect (MCE) in two systems of non-interactive particles: the first corresponds to the Landau problem case and the second the case of an electron in a quantum dot subjected to a parabolic confinement potential. In the first scenario, we realize that the effect is totally different from what happens when the degeneracy of a single electron confined in a magnetic field is not taken into account. In particular, when the degeneracy of the system is negligible, the magnetocaloric effect cools the system, while in the other case, when the degeneracy is strong, the system heats up. For the second case, we study the competition between the characteristic frequency of the potential trap and the cyclotron frequency to find the optimal region that maximizes the ΔT of the magnetocaloric effect, and due to the strong degeneracy of this problem, the results are in coherence with those obtained for the Landau problem. Finally, we consider the case of a transition from a normal MCE to an inverse one and back to normal as a function of temperature. This is due to the competition between the diamagnetic and paramagnetic response when the electron spin in the formulation is included.

scholarly journals Magnetocaloric Effect in Non-Interactive Electrons Systems: ``The Landau Problem'' and Its Extension to Quantum Dot

2018 ◽  
Author(s):  
Oscar A. Negrete ◽  
Francisco J. Peña ◽  
Juan M. Florez ◽  
Patricio Vargas
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Magnetocaloric Effect ◽  
Cyclotron Frequency ◽  
The Other ◽  
Optimal Region ◽  
Potential Trap ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
Strong Degeneration

In this work, we report the magnetocaloric effect (MCE) in two systems of non-interactive particles, the first corresponds to the Landau problem case and the second, the case of an electron in a quantum dot subjected to a parabolic confinement potential. In the first scenario, we realize that the effect is totally different from what happens when the degeneration of a single electron confined in a magnetic field is not taken into account. In particular, when the degeneracy of the system is negligible, the magnetocaloric effect cools the system, while in the other case, when the degeneracy is strong, the system heats up. For the second case, we study the competition between the characteristic frequency of the potential trap and the cyclotron frequency to find the optimal region that maximizes the ΔT of the magnetocaloric effect, and due to the strong degeneration of this problem, the results are in coherence with those obtained for the Landau problem. Finally, we consider the case of a transition from a normal MCE to an inverse one and back to normal as a function of temperature. This is due to the competition between the diamagnetic and paramagnetic response when the electron spin in the formulation is included.

scholarly journals Magnetocaloric Effect in an Antidot : The Effect of the Aharonov-Bohm Flux and Antidot Radius

2018 ◽  
Author(s):  
Oscar A. Negrete ◽  
Francisco J. Peña ◽  
Patricio Vargas
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Magnetocaloric Effect ◽  
Control Parameter ◽  
Energy Levels ◽  
Oscillatory Behaviour ◽  
Confinement Potential ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
Aharonov Bohm

In this work, we report the magnetocaloric effect (MCE) in a quantum dot corresponding to an electron interacting with an antidot, under the effect of an Aharonov-Bohm flux subjected to a parabolic confinement potential. We use the Bogachek and Landman model, which additionally allows the study of quantum dots with Fock-Darwin energy levels for vanishing antidot radius and flux. We find that the Aharonov-Bohm flux (AB-flux) strongly controls the oscillatory behaviour of the MCE, thus acting as a control parameter for the cooling or heating of the magnetocaloric effect. We propose a way to detect AB-flux by measuring temperature differences.

scholarly journals Magnetocaloric Effect in an Antidot: The Effect of the Aharonov-Bohm Flux and Antidot Radius

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 888 ◽  
Author(s):  
Oscar Negrete ◽  
Francisco Peña ◽  
Patricio Vargas
Keyword(s):  
Quantum Dots ◽  
Magnetocaloric Effect ◽  
Control Parameter ◽  
Energy Levels ◽  
Oscillatory Behaviour ◽  
Confinement Potential ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
Aharonov Bohm

In this work, we report the magnetocaloric effect (MCE) for an electron interacting with an antidot, under the effect of an Aharonov-Bohm flux (AB-flux) subjected to a parabolic confinement potential. We use the Bogachek and Landman model, which additionally allows the study of quantum dots with Fock-Darwin energy levels for vanishing antidot radius and AB-flux. We find that AB-flux strongly controls the oscillatory behaviour of the MCE, thus acting as a control parameter for the cooling or heating of the magnetocaloric effect. We propose a way to detect AB-flux by measuring temperature differences.

scholarly journals Investigation of Light Absorption in a ZnS Quantum Dot

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Hojjatollah K. Salehani ◽  
Maedeh Zakeri
Keyword(s):  
Magnetic Field ◽  
Optical Absorption ◽  
Quantum Dot ◽  
Excited States ◽  
Light Absorption ◽  
Blue Shift ◽  
Optical Absorption Coefficient ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
The Magnetic Field

The light absorption of a ZnS quantum dot with a parabolic confinement potential is studied in this paper in the presence of magnetic field perpendicular to dot plane. The Schrodinger equation of a single electron is solved numerically, and energy spectra and wave functions are obtained. Then, the optical absorption coefficients in transition from ground state to different excited states are calculated. The effects the magnetic field and quantum dot width on the optical absorption are investigated. It is found that the optical absorption coefficient has a blue shift by increasing of magnetic field or confinement strength of quantum dot.

TUNNELING EFFECTS EMERGING FROM MULTI-ELECTRON SYSTEMS IN SPATIALLY MODULATED NANOSTRUCTURES

1999 ◽  
Vol 13 (21n22) ◽  
pp. 2689-2703 ◽  
Author(s):  
RYUICHI UGAJIN
Keyword(s):  
Quantum Dots ◽  
Configuration Space ◽  
Dimensional Space ◽  
Quantum States ◽  
The Other ◽  
Electron Interaction ◽  
High Dimensional ◽  
Electron Systems ◽  
Confining Potential ◽  
Number Of Particles

We can see tunneling effects in high-dimensional space through multi-particle states. This is because multi-particle states of quanta are defined in the configuration space with (DN)-dimensions, where N is the number of particles and D is the number of dimensions of our space, though we know the statistics of quanta affect the structure of quantum states. Two examples are reviewed: one is quasi-resonance due to electron–electron interaction in a pair of coupled quantum dots under an external electric field and the other is Hubbard-gap tunneling in which an electron tunnels through Mott insulating electrons in a quantum-dot chain under an overall confining potential.

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