Electron Spin Transport in Quantum Dots and Point Contacts PDF Download
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Author: Erik Johan Koop
Publisher:
ISBN: 9789036735308
Category :
Languages : en
Pages : 132
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Book Description
Author: Erik Johan Koop
Publisher:
ISBN: 9789036735308
Category :
Languages : en
Pages : 132
Get Book Here
Book Description
Author: Tai-Min Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 109
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Book Description
We report several detailed experiments on electron transport through Quantum Point Contacts (QPCs) and lateral Quantum Dots (QDs), created in a Single-Electron Transistor (SET). In the experiment for QPCs, we present a zero-bias peak (ZBP) in the differential conductance, G, which splits in an external magnetic field. The observed splitting closely matches the Zeeman energy and shows very little dependence on gate voltage, suggesting that the mechanism responsible for the formation of the peak involves electron spin. We also show that the mechanism that leads to the formation of the ZBP is different from the conventional Kondo effect found in QDs. In the second experiment, we present transport measurements of a QD in a spin-flip cotunneling regime and a quantitative comparison of the data to the microscopic theory by Lehman and Loss. The differential conductance is measured in the presence of an in-plane Zeeman field. We focus on the ratio of the nonlinear G at bias voltages exceeding the Zeeman threshold to G for those below the threshold. The data show good quantitative agreement with the theory with no adjustable parameters. We also compare the theoretical results to the predictions of a phenomenological form used for the determination of a heterostructure g-factor and find good agreement between the two. In the third experiment, we report the magnetic splitting, [Delta] K, of a Kondo peak in G for a QD while tuning the Kondo temperature, TK, along two different paths in the parameter space: varying the dot-lead coupling at a constant dot energy, and vice versa. At a high magnetic field, B, the changes of [Delta] K with TK along the two paths have opposite signs, indicating that [Delta] K is not a universal function of TK. At low B, we observe a decrease in [Delta]K with TK along both paths, in agreement with theoretical predictions. Furthermore, we find [Delta] K / [Delta]1 at low B and [Delta] K / [Delta] 1 at high B, where [Delta] is the Zeeman energy of the bare spin, in the same system. In the last experiment, we report the zero-bias differential conductance, of an SET in the Kondo regime as a function of temperature, T, and an in-plane magnetic field B. Scaled plots of both the T- and B-dependent data show universal behavior. At moderate and high B, the magnetoconductance data show good agreement with renormalization group calculations in the spin-1/2 Kondo regime. At very low B, we observe a non-monotonic behavior, which may due to the presence of multiple orbital dot levels with similar energies. Further study is required to confirm this assumption.
Author: Jonathan P. Bird
Publisher: Springer Science & Business Media
ISBN: 1461504376
Category : Science
Languages : en
Pages : 481
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Book Description
When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the debate of critical issues in this still developing field. In this matter, I have been assisted greatly by the excellent series of articles provided by the different authors, who are widely recognized as some of the leaders in this vital area of research.
Author: Supriyo Bandyopadhyay
Publisher: CRC Press
ISBN: 148225557X
Category : Science
Languages : en
Pages : 650
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Book Description
Introduction to Spintronics provides an accessible, organized, and progressive presentation of the quantum mechanical concept of spin and the technology of using it to store, process, and communicate information. Fully updated and expanded to 18 chapters, this Second Edition:Reflects the explosion of study in spin-related physics, addressing seven
Author: Jeroen Martijn Elzerman
Publisher: Delft University Press
ISBN: 9789040725333
Category : Technology & Engineering
Languages : en
Pages : 147
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Book Description
Introduction, Few-electron quantum dot circuit with integrated charge read-out, Excited-state spectroscopy on a nearly closed quantum dot via charge detection, Real-time detection of single electron tunneling using a quantum point contact, Single-shot read-out of an individual electron spin in a quantum dot, Semiconductor few-electron quantum dots as spin qubits, the Kondo effect in the unitary limit, Kondo effect in an integer-spin quantum dot, Electron cotunneling in a semiconductor dot, Summary.
Author: A. M. Bychkov
Publisher:
ISBN:
Category :
Languages : en
Pages : 4
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Book Description
We investigate theoretically the effect of spontaneous electron spin polarization in quantum point contacts and quantum dots. Self-consistent calculation process has been developed in the framework of Kohn-Sham LSDA scheme. The existence of the detected spin-polarized states in the low-density regime can be used to explain an anomalous 0.7-structure in the conductance of quantum point contacts. The properties of the potential device based on such an effect are briefly discussed.
Author: Anasuya Erin Krishnaswamy
Publisher:
ISBN:
Category : Electron transport
Languages : en
Pages : 286
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Book Description
Much experimental research has been performed in the equilibrium regime on individual quantum dots and quantum point contacts (QPCs). The focus of the research presented here is electron transport in the nonequilibrium regime in coupled quantum dot and QPC systems fabricated on AlGaAs/GaAs material using the split gate technique. Near equilibrium magnetoconductance measurements were performed on a quantum dot and a QPC. Oscillations were seen in the conductance of the sensor which corresponded to Aharonov-Bohm oscillations in the quantum dot, to our knowledge the first such observation. Sudden jumps in the conductance of the QPC were observed under certain gate biases and under certain magnetic fields. When the gate biases and magnetic field were held constant and the conductance was observed over time, switching was observed with the form of a random telegraph signal (RTS). RTS switching is usually attributed to charging of a single impurity. However, in this case switching may have been due to tunneling via edge states in the dot. Nonequilibrium transport in single quantum dots was investigated. A knee or kink was observed in the current-voltage characteristics of two dots on different material. The bias conditions under which the knee occurred point to electron heating as the physical mechanism for the observed behavior. However, the data can not be fit accurately over all bias ranges with an energy balance hot electron model. Modifications to the model are needed to accurately represent the devices studied here. Finally, the effect of nonlinear transport through a one dimensional (1D) QPC on the equilibrium conductance of an adjacent OD quantum dot was explored. This was the first attempt to observe Coulomb drag between a OD and 1D system. It was observed that the equilibrium conductance peaks in the quantum dot were broadened as the current in the QPC increased. This apparent electron heating effect in the dot can be explained by a simple ballistic phonon model. However, reasonable phase coherence times can be estimated from peak fitting using a Breit- Wigner formula which points to a Coulomb interaction. More detailed numerical calculations should illuminate the dominant scattering processes.
Author: Nakul Shaji
Publisher:
ISBN:
Category :
Languages : en
Pages : 198
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Book Description
Author: Lydia L. Sohn
Publisher: Springer Science & Business Media
ISBN: 9401588392
Category : Science
Languages : en
Pages : 680
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Book Description
Ongoing developments in nanofabrication technology and the availability of novel materials have led to the emergence and evolution of new topics for mesoscopic research, including scanning-tunnelling microscopic studies of few-atom metallic clusters, discrete energy level spectroscopy, the prediction of Kondo-type physics in the transport properties of quantum dots, time dependent effects, and the properties of interacting systems, e.g. of Luttinger liquids. The overall understanding of each of these areas is still incomplete; nevertheless, with the foundations laid by studies in the more traditional systems there is no doubt that these new areas will advance mesoscopic electron transport to a new phenomenological level, both experimentally and theoretically. Mesoscopic Electron Transport highlights selected areas in the field, provides a comprehensive review of such systems, and also serves as an introduction to the new and developing areas of mesoscopic electron transport.
Author: Evgeny Y. Tsymbal
Publisher: CRC Press
ISBN: 1439803773
Category : Science
Languages : en
Pages : 809
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Book Description
In the past several decades, the research on spin transport and magnetism has led to remarkable scientific and technological breakthroughs, including Albert Fert and Peter Grünberg’s Nobel Prize-winning discovery of giant magnetoresistance (GMR) in magnetic metallic multilayers. Handbook of Spin Transport and Magnetism provides a comprehensive, balanced account of the state of the art in the field known as spin electronics or spintronics. It reveals how key phenomena first discovered in one class of materials, such as spin injection in metals, have been revisited decades later in other materials systems, including silicon, organic semiconductors, carbon nanotubes, graphene, and carefully engineered nanostructures. The first section of the book offers a historical and personal perspective of the field written by Nobel Prize laureate Albert Fert. The second section addresses physical phenomena, such as GMR, in hybrid structures of ferromagnetic and normal metals. The third section discusses recent developments in spin-dependent tunneling, including magnetic tunnel junctions with ferroelectric barriers. In the fourth section, the contributors look at how to control spin and magnetism in semiconductors. In the fifth section, they examine phenomena typically found in nanostructures made from metals, superconductors, molecular magnets, carbon nanotubes, quantum dots, and graphene. The final section covers novel spin-based applications, including advanced magnetic sensors, nonvolatile magnetoresistive random access memory, and semiconductor spin-lasers. The techniques and materials of spintronics have rapidly evolved in recent years, leading to vast improvements in hard drive storage and magnetic sensing. With extensive cross-references between chapters, this seminal handbook provides a complete guide to spin transport and magnetism across various classes of materials and structures.
