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1
Content available remote

Optical Responses in Asymmetric Inverse Parabolic Quantum Wells: Effects of Laser Fields and Hydrostatic Pressure

100%
Mora-Ramos M., Morales A., Duque C.
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vol. 125
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issue 2
202-204
EN
We report the theoretical calculation of the electronic states in a Al_{x}Ga_{1-x}As-based quantum well with inverse parabolic confinement under the combined effects of the intense laser field and hydrostatic pressure. Calculations are in the effective mass and parabolic band approximations and using a variational procedure and the so-called Floquet method in order to obtain the energies and wave functions for the conduction band states. We use the obtained information to investigate the intersubband-related nonlinear optical absorption and optical rectification coefficients.
2
Content available remote

Nonlinear Optical Rectification and Second Harmonic Generation in 2D Quantum Rings under Electric Field and Magnetic Fields

100%
Morales A., Mora-Ramos M., Duque C.
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vol. 125
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issue 2
195-197
EN
By using the effective mass and parabolic band approximations, the nonlinear optical rectification and the second harmonic generation are calculated in a two-dimensional quantum ring under the simultaneous effects of perpendicularly applied magnetic field and in-plane applied electric field. The geometry of the ring is modeled via the combined influences of a parabolic and inverse square confining potentials. The exact solutions for the two-dimensional motion of the conduction band electrons are used as the basis for a perturbation-theory treatment of the static electric field effect. The variation of one of the different potential energy parameters, for a fixed configuration of the remaining ones, leads to either blueshifts or redshifts of the resonant peaks as well as to distinct rates of change for their amplitudes.
3
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Double-Donor Energy Structure in Concentric Quantum Rings under Magnetic Field and Hydrostatic Pressure

88%
Fulla M., Marín J., Londoño D., Duque C., Mora-Ramos M.
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vol. 125
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issue 2
220-223
EN
A model for an artificial hydrogen molecule consisting of two positive on-axis Coulombic centers and two electrons coupled to them inside a double concentric quantum ring is considered. Such a nanostructure is assumed to be under the influence of external probes like hydrostatic pressure and magnetic field. By using the adiabatic approximation, the ground state energy is calculated as a function of the outer center line radius and the impurity Coulombic center separation, for different values of the hydrostatic pressure and magnetic field strength. In contrast to the single properties imposed by nature on the actual hydrogen molecule, our model allows us to explore a great variety of properties of the artificial hydrogen molecule by changing the ring dimensions. The artificial hydrogen molecule energy structure may be tuned by changing the external field strengths.
4
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D_2^+ Molecular Complex in Ring-Like Nanostructures: Hydrostatic Pressure and Electromagnetic Field Effects

88%
Fulla M., Marín J., Gutiérrez W., Duque C., Mora-Ramos M.
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vol. 125
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issue 2
241-244
EN
In this work we investigate the energy states in a D_2^+ complex formed by the coupling of a conduction band electron and two donor centers in a quantum ring with rectangular cross-section. The influences of externally applied probes like electric and magnetic fields and hydrostatic pressure together with the change in the relative position between the two Coulombic centers are particularly studied, highlighting the important contribution of the repulsive inter-center interaction. The destruction of the Aharonov-Bohm oscillations of the ground state associated with the localization of the electron states in the system is discussed.
5
Content available remote

Impurity-Related Nonlinear Optical Absorption in Delta-Doped Quantum Rings

88%
Restrepo R., Martínez-Orozco J., Barseghyan M., Mora-Ramos M., Duque C.
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vol. 125
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issue 2
245-247
EN
Using a variational procedure within the effective mass approximation, we have calculated the hydrogenic impurity binding energy as well as the impurity-related nonlinear optical absorption in a single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is analytically modeled with a Hartree-like confining profile fitted to a one-dimensional Thomas-Fermi-based potential in the local density approximation. Both on-center and on-edge impurity positions are considered and the energies of the impurity states are examined as functions of the vertical size of the ring. It is found that the effect of changes in the geometry of the quantum ring leads to a shifting of the resonant peaks of the intra-band optical spectrum.
6
Content available remote

Intense Laser Field Effects on the Shallow-Donor Impurity States in Rectangular-Shaped Quantum Well Wires

64%
Duque C., Mora-Ramos M., Yesilgul U., Ungan F., Sakiroglu S., Kasapoglu E., Sari H., Sökmen I.
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vol. 125
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issue 2
198-201
EN
Using the effective mass and parabolic band approximations, the binding energy of a shallow donor impurity is calculated in a GaAs-(Ga,Al)As quantum well wire of rectangular transversal section, under the combined effects of two independent axially-applied intense laser radiation fields and a static electric field oriented in the cross-section plane. The lateral size of the rectangular cross-section is assumed to be larger than 10 nm, in such a way that the uncorrelated electron motion along the x and y directions can be considered uncoupled. The impurity-related states are calculated by means of a variational procedure using a three-dimensional hydrogen-like trial wave function. The intense laser field effects are introduced via the combination of the Floquet method for the laser-modified confinement potential shape and the inclusion of a two-interaction centers model for the Coulombic coupling. It is shown that, according to the polarization of the incident radiation, the quantum well wire can evolve from a single 1D-heterostructure towards a configuration of two-well defined or four-well defined laser-induced parallel coupled quantum well wires. The obtained results also show that the binding energy is strongly dependent on the impurity position and on the strength of the intense laser field parameter.
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