scholarly journals Tracking electron pathways with magnetic field: Aperiodic Aharonov-Bohm oscillations in coherent transport through a periodic array of quantum dots

2015 ◽  
Vol 91 (4) ◽  
Author(s):  
L. S. Petrosyan ◽  
T. V. Shahbazyan
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Periodic Array ◽  
Coherent Transport ◽  
Aharonov Bohm

scholarly journals Thermoelectric coefficients and the figure of merit for large open quantum dots

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Robert Whitney ◽  
Keiji Saito
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
External Magnetic Field ◽  
Figure Of Merit ◽  
Matrix Theory ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Coherent Transport ◽  
Left And Right ◽  
The Magnetic Field

We consider the thermoelectric response of chaotic or disordered quantum dots in the limit of phase-coherent transport, statistically described by random matrix theory. We calculate the full distribution of the thermoelectric coefficients (Seebeck S and Peltier \PiΠ), and the thermoelectric figure of merit ZT, for large open dots at arbitrary temperature and external magnetic field, when the number of modes in the left and right leads (N_{\rm L} and N_{\rm R}) are large. Our results show that the thermoelectric coefficients and ZT are maximal when the temperature is half the Thouless energy, and the magnetic field is negligible. They remain small, even at their maximum, but they exhibit a type of universality at all temperatures, in which they do not depend on the asymmetry between the left and right leads (N_{\rm L}-N_{\rm R}), even though they depend on (N_{\rm L}+N_{\rm R}).

NUMERICAL STUDY OF TRANSPORT PROPERTIES IN TOPOLOGICAL INSULATOR QUANTUM DOTS UNDER MAGNETIC FIELD

2013 ◽  
Vol 27 (14) ◽  
pp. 1350104 ◽  
Author(s):  
SHENG-NAN ZHANG ◽  
HUA JIANG ◽  
HAIWEN LIU
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Transport Properties ◽  
Topological Insulator ◽  
Numerical Study ◽  
Spin Polarized ◽  
Full Band ◽  
Spin Degeneracy ◽  
Aharonov Bohm ◽  
The Magnetic Field

In this paper, we investigate the transport properties of HgTe / CdTe -based topological insulator quantum dots (TIQDs) under magnetic field. Both disk and square shaped TIQDs are considered and the magneto-conductance are calculated numerically for various magnetic field strength. The magnetic field lifts the spin degeneracy, leading to spin polarized current at given Fermi energy. Meanwhile, the magneto-conductance demonstrates the Aharonov–Bohm (AB) oscillation with a period of one flux quantum [Formula: see text]. Numerical results for AB oscillation features indicate the mismatch between electron (e) and hole (h) doping conditions, which can be attributed to the e–h asymmetry in the full band Hamiltonian. Further, interference effect emerges around bulk and edge energy degenerate points, subsequently suppressing the magneto-conductance in both shaped systems. All these physical characteristics are qualitatively consistent for disk and square shaped TIQDs due to the topological nature of edge modes.

scholarly journals Efecto Aharonov-Bohm en puntos cuánticos no uniformes

2015 ◽  
Vol 3 (1) ◽  
pp. 9-17
Author(s):  
Adriana Lucia Gélvez ◽  
Willian Gutierrez ◽  
Fredy Rodríguez Prada
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Energy Levels ◽  
Outer Radius ◽  
Structural Defects ◽  
Isotropic Case ◽  
Dimensional System ◽  
Quantum Rings ◽  
Low Dimensional ◽  
Aharonov Bohm

Introducción: Recientemente, las investigaciones en el campo de la materia condensada se han venido enfocando en el estudio de estructuras fabricadas mediante diferentes técnicas de crecimiento de cristales, en especial de materiales semiconductores y esto ha despertado un gran interés en el estudio teórico y aprovechamiento tecnológico de las importantes propiedades que despliegan los sistemas de partículas confinadas en puntos cuánticos con diferentes morfologías (nano-estructuras semiconductoras cero-dimesionales). Un atractivo especial en el área de los sistemas de baja dimensionalidad es el estudio de las propiedades opto-electrónicas de puntos cuánticos en forma de irregulares. Los Anillos Cuánticos, especialmente, son estructuras que poseen simetría axial y presentan una cavidad semiconductora en la región comprendida entre su radio interno y externo. Debido al confinamiento periódico el comportamiento de los portadores de carga en esta estructura deben tener un carácter diferente en presencia de un campo magnético externo, como sucede con el denominado Efecto Oscilatorio Aharonov-Bohm (AB). Este fenómeno se observa generalmente cuando una partícula cargada confinada en un sistema de baja dimensionalidad está afectada por un campo electromagnético externo. Materiales y Métodos: Se analiza el efecto de la irregularidad morfológica en puntos cuánticos lenticulares y de anillos cuánticos tipo cráter, que se encuentran sometidos a un campo magnético en la dirección de crecimiento, sobre el espectro energético de un electrón confinado en cada uno de ellos. Resultados y discusión: Los defectos estructurales son modelados mediante funciones en coordenadas cilíndricas, las cuales presentan soluciones analíticas para los casos isotrópicos. Posteriormente, los resultados de los estados energéticos del electrón en las estructuras simétricas permiten obtener el comportamiento de la energía para problemas completos y complejos mediante el uso de métodos numéricos, como diagonalización exacta y expansión en series. Conclusiones: Se presentan en este trabajo los niveles energéticos de un electrón en función de intensidad del campo magnético y se reportan comportamientos diferentes para ambos tipos de QDs considerados, principalmente porque en los de tipo cráter se presentan oscilanes AB, característico de anillos cuánticos unidimensionales. En este estudio el surgimiento de oscilaciones AB, en puntos cuántico tipo cráter se debe a la mayor probabilidad de ubicar al electrón en el borde de la estructura, ya que esta zona es la de menor confinamiento cuántico. Introduction: Recently, research in the field of condensed matter have been focusing on the study of structures fabricated by different techniques of crystal growth, especially semiconductor materials this has aroused great interest in the theoretical study and technological performance of the important properties that display particle systems confined in quantum dots with differentmorphologies (semiconductor nanostructures zero - dimensional). A special interest in the field of low - dimensional systems is the study of opto - electronic properties of quantum dots with irregular shapes. Quantum Rings, especially, are semiconductor structures having axial symmetry and have a cavity in the region between the inner and outer radius. Due to the periodic confinement the behavior of charge carriers in such structures should have a different character in the presence of an external magnetic field, as with the so-called Aharonov-Bohm Effect (AB). This phenomenon is usually observed when a charged particle confined in a low dimensional system is affected by an external electromagnetic field. Materials and methods: We analyzes the effect of morphological irregularity of lenticular- like and crater-like quantum dots, and the effect of a magnetic field applied in the growth direction on the energy spectrum of an electron confined in these structures. Results and discussion: Structural defects are modeled by functions in cylindrical coordinates, which presented analytical solutions for the isotropic case. Subsequently, the results of energy states of the electron in symmetrical structures allow obtain the energy to complete and complex problems by using numerical methods, as exact diagonalization and series expansion. Conclusions: We present the energy levels of an electron as a function of magnetic field intensity and shown different behaviors for both types of QDs considered, mainly AB oscillations in crater-like quantum dots, characteristic phenomena of one-dimensional quantum rings. This effect is due to the higher probability of finding the electron in the outer border of the structure, because this region has the lowest quantum confinement.

Thermoelectric Power in Quantum Confined Bismuth Under Classically Large Magnetic Field

1990 ◽  
Vol 216 ◽  
Author(s):  
Kamakhya P. Ghatak ◽  
S. N. Biswas
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Quantum Well ◽  
Film Thickness ◽  
Quantum Wells ◽  
Thermoelectric Power ◽  
Large Magnetic Field ◽  
Quantum Well Wires ◽  
Electron Dispersion ◽  
Theoretical Results

ABSTRACTIn this paper we studied the thermoelectric power under classically large magnetic field (TPM) in quantum wells (QWs), quantum well wires (QWWS) and quantum dots (QDs) of Bi by formulating the respective electron dispersion laws. The TPM increases with increasing film thickness in an oscillatory manner in all the cases. The TPM in QD is greatest and the least for quantum wells respectively. The theoretical results are in agreement with the experimental observations as reported elsewhere.

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