Theoretical Study of Charge and Spin-resolved Quantum Transport in III-V Semiconductor Nanostructures PDF Download

Author: André Erasmus Botha
Publisher:
ISBN:
Category : Nanostructures
Languages : en
Pages : 314

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Author: André Erasmus Botha
Publisher:
ISBN:
Category : Nanostructures
Languages : en
Pages : 0

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 942

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Author: Marc Vila Tusell
Publisher: Springer Nature
ISBN: 3030861147
Category : Technology & Engineering
Languages : en
Pages : 169

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This thesis focuses on the exploration of nontrivial spin dynamics in graphene-based devices and topological materials, using realistic theoretical models and state-of-the-art quantum transport methodologies. The main outcomes of this work are: (i) the analysis of the crossover from diffusive to ballistic spin transport regimes in ultraclean graphene nonlocal devices, and (ii) investigation of spin transport and spin dynamics phenomena (such as the (quantum) spin Hall effect) in novel topological materials, such as monolayer Weyl semimetals WeTe2 and MoTe2. Indeed, the ballistic spin transport results are key for further interpretation of ultraclean spintronic devices, and will enable extracting precise values of spin diffusion lengths in diffusive transport and guide experiments in the (quasi)ballistic regime. Furthermore, the thesis provides an in-depth theoretical interpretation of puzzling huge measured efficiencies of the spin Hall effect in MoTe2, as well as a prediction of a novel canted quantum spin Hall effect in WTe2 with spins pointing in the yz plane.

Author: Patrik Brusheim Johansson
Publisher:
ISBN: 9789162875275
Category :
Languages : en
Pages : 91

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Author: Paul Harrison
Publisher: Wiley
ISBN: 9780470770979
Category : Science
Languages : en
Pages : 0

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Quantum Wells, Wires and Dots, 3rd Edition is aimed at providing all the essential information, both theoretical and computational, in order that the reader can, starting from essentially nothing, understand how the electronic, optical and transport properties of semiconductor heterostructures are calculated. Completely revised and updated, this text is designed to lead the reader through a series of simple theoretical and computational implementations, and slowly build from solid foundations, to a level where the reader can begin to initiate theoretical investigations or explanations of their own.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 44

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The objective of this research program is to study theoretically the underlying principles of solid-state dynamics and quantum mechanical transport of carriers in ultrasmall novel semiconductor devices. The areas of research are: (1) theory of phonon modes in reduced dimensions, (2) effects of band structure on electronic and optical properties of heterostructures, and (3) quantum transport in solids with special emphasis on non-perturbative role of high-electric fields and many-body effects in dynamical processes. The treatment of these problems is mainly analytical through the development of macroscopic and microscopic physical models with an emphasis on quantum mechanical principles. At the same time, numerical approaches has also been utilized for realistic solutions with accuracy. Specific subjects discussed in this report include the effects of confinement and localization on optical phonon modes, band mixing in tunneling, Bloch electron quantum transport theory under hot- electron conditions, and dielectric response function theory.

Author: Tillmann Christoph Kubis
Publisher:
ISBN: 9783941650145
Category :
Languages : en
Pages : 253

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Author: Kazi Monirul Alam Alam
Publisher:
ISBN:
Category : Magnetism
Languages : en
Pages : 107

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Electrons, the fundamental charge carriers in solid-state devices, possess three intrinsic properties: mass, charge and spin. Spin is a quantum mechanical property, but can be loosely visualized as a tiny "intrinsic" magnetic dipole moment attached to an electron. In conventional electron devices, spin magnetic moments point along random directions in space and play no significant role in device operation. In the emerging field of "spintronics" the central theme is to harness the spin degree of freedom of charge carriers to realize novel data storage and information processing technologies. Spintronic devices are already ubiquitous in state-of-the-art hard disks with large storage densities. A concerted global effort is underway to explore various spin-based information processing concepts, which can potentially be more energy-efficient than traditional charge-based electronics. In recent years, substantial research has been devoted to understanding carrier spin dynamics in metallic multilayers, tunnel junctions and inorganic semiconductors such as silicon, germanium and various III-V compounds. On the other hand, p-conjugated organic semiconductors that play a crucial role in organic electronics and displays are relatively new materials in the area of spintronics. Organic semiconductors offer several advantages (such as mechanical flexibility, chemical tunability of physical properties, low-cost and low-temperature processing) compared to their inorganic counterparts. The ability to control carrier spin dynamics in organic materials will open up possibility of new devices such as flexible non-volatile memories, spin-based organic light emitting diodes and spin filters. iii In this work, we have explored two key spin related phenomena in organic semiconductor nanostructures: (a) spin-polarized transport and (b) spin filtering. In the first sub-project, we explore spin transport in "nanowire" geometry instead of commonly studied thin film devices. Such experiments shed light on the spin relaxation mechanisms in organics and indicate ways to minimize such effects. Fabrication of organic nanowires with well-controlled geometry in the sub-100 nm range is a non-trivial task, and in this subproject we have developed a novel technique for this purpose. Spin transport in rubrene nanowires has been studied, which indicates significant suppression of spin relaxation in nanowire geometry compared to rubrene thin films. Our experimental data indicates that spin-orbit coupling is the dominant spin relaxation mechanism in rubrene nanowires. In the second sub-project, we explore spin filtering (transmission of one particular type of spin) through an organic nanostructure in which single wall carbon nanotubes (SWCNT) are wrapped with single stranded DNA (ssDNA) molecules. Efficient spin filtering has been observed in this system, which may enable magnetless spintronic devices in the future.

Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 816

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